Workshop: "The Idiot's Guide to Kryptonite and Other Kryptonian Weaknesses" by Saavikam77
The Idiot's Guide to Kryptonite and Other Kryptonian Weaknesses
or
Gentlemen, how do we kill Superman?
In my essay, Writing Clark Kent, I discussed the myriad powers he possesses. But what about his weaknesses? Here, we'll look at all the things that can hurt the average Kryptonian, including the many forms of kryptonite.
There are seven categories of Kryptonian weaknesses:
1. Kryptonite
2. Magic
3. Red solar radiation
4. Exhausted power reserves and overwhelming force
5. Overloaded powers
6. Internal attacks (viruses and other disease, mind control)
7. The Phantom Zone
Kryptonite
The perennial favorite of villains everywhere, kryptonite has been used as a foil for Superman ever since the early days of the radio show, when it was created in order to give the voice actor, Bud Collyer, a day off of work. First appearing in pre-Crisis comics as a green crystal, it was later joined by a red variety, and eventually, the group of kryptonite varieties expanded to include nearly the entire rainbow, as well as forms such as Kryptonite-X and Slow Kryptonite.
Origins and Science
Most forms of kryptonite were once part of the core of the planet Krypton. When Krypton was destroyed, its core (and possibly the entire crust as well) was irradiated in such a way the minerals were transformed into a radioactive form that is capable of killing Kryptonians. This was the original Green Kryptonite. In pre-Crisis comics, Red Kryptonite was created when large quantities of green kryptonite passed through a cloud of unknown gases in space as it followed the trajectory the infant Kal-El's spaceship took to reach Earth. Post-Crisis, Red K was first made by Mr. Mxyzptlk, then created synthetically by Ra's al Ghul.
Other forms have been created from green kryptonite through various means, including heating, laboratory experiments, magical transformation, and possibly exposure to other elements in space. A few varieties are completely man-made.
The composition of kryptonite has been speculated to be everything from a stable transuranic element with the atomic number 126 and a half-life of 250,000 years, to the complex crystal molecule 'lithium boron silicate hydroxide with fluorine', as seen in Superman Returns. In any case, it has nothing to do with the element Krypton, which is a noble gas that does not usually bond with any other element, and is used in some light bulbs.
But what does kryptonite do? Well, in its original form (Green), it is speculated that the radiation disrupts the cellular processes that are responsible for a Kryptonian's strength and other powers. It drives the stored energy out of the cells entirely (essentially destroying the energy-laden bonds within certain molecules), leaving the Kryptonian weak, powerless, and sick. After long or intense exposure, the result is death.
Kryptonite does also affect other beings, since it is a radioactive substance. The result of a long exposure is radiation sickness, as evidenced by Lex Luthor's bout with cancer and the subsequent loss of one of his hands in the comics.
In all canon, all forms of kryptonite radiation can be blocked by lead.
Varieties
Green Kryptonite
Canon: All canon
Effects: Robs any super-powered Kryptonian of their powers, makes them weak and sick, including causing severe pain and nausea, and giving a green tinting to the skin and irises. Exposure leaves the Kryptonian vulnerable to injury, and prolonged exposure leads to death. In some current comics it does not rob the affected Kryptonian of their powers immediately, but leaves them sick and in severe pain.
In Smallville, Green Kryptonite can mutate human DNA, granting a wide variety of powers as well as potentially leaving the affected person mentally unstable and prone to violence.
Red Kryptonite
Canon: Comics, Smallville, Super Friends, Lois and Clark, Krypto the Superdog
Effects: In the comics, the effects of Red K vary from one exposure to the next. It may cause anything from lowered inhibitions to anger to apathy to growing a third eye.
From Wikipedia:
“Superman has suffered the following random effects upon exposure to various pieces of red kryptonite: being turned into a dragon, a non-powered giant, a dwarf, an ant-headed humanoid, a lunatic, and an amnesiac; being made unable to see anything colored green; growing incredibly long hair, nails, and beard; being rendered totally powerless; growing fat; gaining the ability to read thoughts; growing a third eye in the back of his head; losing his invulnerability along the left side of his body; being split into an evil Superman and a good Clark Kent; being split into young and old forms (Superboy and Superman); being rendered unable to speak or write anything but Kryptonese; growing an extra set of arms; becoming clumsy; swapping bodies with the person nearest him upon exposure to it; transferring his powers; rapidly aging; multiple personality changes; and having his skin rendered transparent, overloading him with solar power.”
In Smallville canon, Red K only works upon contact with skin, and induces a drug-like effect, resulting in the loss of inhibitions, unpredictability, and general selfishness and eroticism. It has the same effect with every exposure, and the effects last as long as close contact with the mineral is maintained.
Outside of Smallville, the effects of Red K generally last 24-48 hours, after which the affected Kryptonian will be immune to that particular piece of Red K.
Blue Kryptonite
Canon: Comics, Super Friends, DCU video games, Smallville
Effects: In the comics, Blue K was created by the same duplicator ray that created Bizarro. In pre-Crisis comics, Blue K hurts Bizarro in the same way that Green K hurts Kryptonians. Post-Crisis, it also makes Bizarro kind and intelligent. Blue K was used to heal Superman from the effects of Red K in one episode of Super Friends, and has been used as a general life restorative on Kryptonians in several video games.
In Smallville, Blue K suppresses Kryptonian super powers and removes the sensitivity to Green K. It also increases Bizarro's powers exponentially.
Gold Kryptonite
Canon: Comics, Super Friends
Effects: Permanently robs the effected Kryptonian of their powers by destroying the cellular machinery responsible for them. Does not cause sickness!
Black Kryptonite
Canon: Comics, Smallville, Superman III
Effects: Originally seen in Smallville, created by super-heating Green K, this variety can split a person (or plants, even) into two distinct beings, one 'good' and one 'bad'. It can also be used to reunite those split halves. It is unclear whether or not Black K can split a Kryptonian fully in two, here (full discussion of the subject is here, if you'd like to break your brain). In the comics, Black K was synthetically created by Darkseid, and can separate a Kryptonian into two distinct beings, along the same lines as the Smallville variety (it was used to split Supergirl into a 'good' version and a 'bad' version, which were fused again by Diana's Golden Lasso). Finally, in All-Star Superman, an AU comic, Black K makes Superman evil.
It's interesting to note that in Superman III, a synthesized version of Green K, containing tar in the place of an unknown element, has a similar effect on Superman, splitting him into two people, one 'good' and one 'bad', after first acting like Red K, making him apathetic, angry, and somewhat violent.
White Kryptonite
Canon: Comics only
Effects: Formed from Green K that passed through a 'cosmic cloud', White K destroys all plant life, whether Kryptonian or not. In one comic, possibly an Elseworlds title, Superman used a small piece of White K to counter the effects of Gold K. This effect only lasted as long as close contact was maintained with the mineral.
Jewel Kryptonite
Canon: Comics only
Effects: Formed from the Jewel Mountains on Krypton, Jewel K amplifies the psychic powers of Phantom Zone residents, permitting them to project illusions into the real world or perform mind-control.
Silver Kryptonite
Canon: Comics, Smallville
Effects: In a Silver-Age comic, Silver K was a hoax used to celebrate the silver anniversary of the creation of “Superman”. In Superman/Batman #46, Silver K was the name initially given to a form of kryptonite that had been magically altered to enslave the mind of the affected person in an escapist fantasy. A version of Silver K in Smallville gave Clark paranoid delusions, but this was also a hoax, as the mineral turned out to be a part of Brainiac.
Magic Kryptonite
Canon: Comics only
Effects: This is the newest addition to the many varieties of K. Originally referred to as Silver Kryptonite, Magic K is actually only two magically enchanted pieces of Kryptonite, one shaped like a crescent moon, and the other its compliment, creating a complete disc when put together. Called the “Ach-Om-Rashay”, or the Amulet of Mindfulness, the pieces (when only one is present) put a spell of mind control, or enslavement, on any person that comes in close contact with them, causing the person to either see or live out an escapist fantasy. In Clark's case, it made him completely care-free, seeming to be 'high'. The spell is countered by exposing the affected person to the other piece. In the comics, the crescent shaped piece was supposedly destroyed by being thrown into the sun, but both were shown later as part of a secret collection in the Bat Cave.
Pink Kryptonite (the perennial favorite with fans! ^_~)
Canon: Comics AU, fanon
Effects: Shown in only one panel in an AU Supergirl storyline by Peter David, Pink K turns heterosexual Kryptonians temporarily and stereotypically gay. It is unknown whether or not the effect works in reverse.
Amber Kryptonite
Canon: Fanon only
Effects: Introduced in quirky_circe's 20 Random Things About Kal-El, Amber K makes the affected Kryptonian “blind stinking drunk”.
Lavender Kryptonite
Canon: Fanon only
Effects: Introduced in ljs_lj's Lavender, Lavender K temporarily changes the sex (and all associated physical features) of the affected Kryptonian.
Other rare forms of kryptonite include Anti-Kryptonite, X-Kryptonite, Slow Kryptonite, Magno-Kryptonite, Bizarro Kryptonite, and Kryptonite X/Kryptisium. None of these forms have any effect on Kryptonians (except for Anti-Kryptonite, which works like Green K on non-super-powered Kryptonians).
Hoaxes include Yellow Kryptonite, 2 forms of Silver Kryptonite, Blood Kryptonite (used by the Cult of Connor in the “52” storyline), Kryptonite Plus, Purple Spotted Kryptonite (which made Krypto chase his tail in Krypto the Superdog), and Fake Kryptonite.
Magic
By far, a Kryptonian's greatest weakness is magic. They are simply completely vulnerable to its whims. The effects don't necessarily include loss of powers or sickness, as the field involved in a magical spell disrupts any defenses the Kryptonian might have, but they can include anything and everything if the spell intends it. On many occasions, Superman has been affected, hurt, or used as a weapon himself under the influence of magic. Considering the potential for trouble when magic is involved, Clark is understandably wary of magic and magic users.
Notable Magic Users
Dr. Fate: Any of a number of people who have worn both the Helm of Nabu, which is possessed by the spirit of the ancient wizard Nabu, and the Amulet of Anubis, which confers vast magical abilities. Dr. Fate is a powerful sorcerer, and has occasionally been an ally to both the Justice Society and the Justice League.
Eclipso: Any of a number of people that have been possessed by the vengeance demon, Eclipso, via a black diamond (of which there are several). Eclipso's magical abilities are generally limited to possession and powers of persuasion/influence.
Felix Faust: A power-hungry master sorcerer with no good intentions. He's often a thorn in the Justice League's side.
Jason Blood: An occasional ally of Batman, he is an adept magic user who is sometimes called in to help with occult matters. As he is bound to the Demon Etrigan (who is a powerful magic user himself and also speaks in rhyme), the two share the same body and occasionally shift from one form to the other.
Mary Marvel: The alter-ego of Mary Batson, she recently came into great magical powers when she absorbed some of Black Adam's power. Under that dark influence, she 'studied' under Zatanna, Eclipso, Klarion the witch boy, and Granny Goodness, increasing her powers and her propensity for evil. Currently, she's working for Darkseid in 'Final Crisis'.
Morgaine le Fey: The ancient, diabolical sorceress of Arthurian legend, she's been an enemy of the Demon Etrigan since Arthurian times. She's immortal, and is a master of vastly powerful black magic, which she uses without restraint.
Mr. Mxyzptlk: Often called Mxy, he is an imp from the Fifth Dimension who tends to use his seemingly unlimited powers to simply cause Superman trouble. The only way to send him back to his home dimension and counter his spells is to trick him into saying his name backwards (Kltpzyxm).
Phantom Stranger: An occasional ally of the Justice League, he is literally a mysterious stranger with unclear origins, who possesses magical abilities with undetermined limits.
The Spectre: A cosmic entity that is best known for being the avenging hand of God, the Spectre is usually bound to a human host. He possesses seeming omnipotence, but does not ally himself with anyone or choose sides. For a time, the Spectre inhabited Hal Jordan.
Zatanna: As the Justice League's usual resident magician, she often has to counter nefarious magical attacks and spells. She speaks all her spells in reverse, and one often quoted panel depicts her shouting the spell, “NAMREPUS, POTS!!” telling Superman to stop what he's doing. Her teen-aged cousin, Zachary, is a similarly powered magician (without the ability to affect humans with his spells) who was at one time a Teen Titan.
Other magic users include Klarion the witch boy, the demon prince Neron, Raven, the wizard Shazam, and Traci Thirteen.
Red Solar Radiation
Kryptonians aren't susceptible to radiation as we think of it, however, the radiation of a red sun (light in the red end of the spectrum) has the potential to weaken Kryptonians by supposedly locking up the cellular machinery responsible for super-human abilities so they can't process the stored energy. This would have the physical effect of rendering the Kryptonian powerless until such a time that the red solar radiation is replaced with yellow.
Some sources have hypothesized that red sun radiation drives the stored energy out of the cells, however, other sources believe that the Kryptonian's loss of powers under the influence of red wavelengths is the result of the gradual withdrawal of yellow wavelengths, of the Kryptonian using up his or her energy reserves and not being able to replenish them. If the former is the case, then the affected Kryptonian will lose his or her powers rapidly. If the latter is true, then the power loss is slow and gradual. With the latter also comes the possibility that under an orange sun, a Kryptonian would retain some of his or her abilities at a diminished level.
Following the events of Infinite Crisis, at the end of which Superman flew through a red sun, Clark was powerless for an entire year. This lends some credence to the theory that red solar radiation drives the stored energy out, though it was also thought that his prolonged power loss was more due to a psychological block.
However it works, the end result of this is that villains have often used red solar radiation in some form as a weapon against Superman and other Kryptonians, even devising prison cells with red solar lamps to keep Superman powerless and incapable of escape.
Exhausted Power Reserves and Overwhelming Force
Contrary to some opinions, Superman's power is not limitless. That goes for every other Kryptonian as well. At some point in a prolonged fight against an extremely powerful opponent or many less powerful opponents, the Kryptonian will begin to tire, all that stored energy used up with no opportunity to recharge. This is the same phenomenon we know as humans: when you run out of energy, you simply can't fight any longer.
The same goes for when a Kryptonian fights a more powerful opponent. They can be overpowered by simple force, and it has happened on many occasions.
Notably powerful people include any of the Green Lanterns, any of the Marvel family, Wonder Woman, Darkseid (the tyrannical ruler of the planet Apokolips), Doomsday (the genetically engineered monster who fought Superman seemingly to the death), Mongul (the tyrannical ruler of Warworld), and Superboy Prime (an alternate dimension Superboy, who has recently grown into Superman Prime).
In addition, weapons with enough energy to inflict damage to the bioelectric 'aura' protecting the Kryptonian could weaken or injure that Kryptonian. A single lightening bolt wouldn't be enough to hurt, but the power of several city blocks once left Superman in severe pain, and he was once knocked out by the blast of a 90 megaton bomb. In one instance on Superman: The Animated Series, he was hurt by extreme amounts of electrical current directed at him by Livewire.
Overloaded Powers
At the opposite end of the spectrum, it's possible to overload a Kryptonian's powers. On a broad scale, too much yellow sun radiation can cause a Kryptonian's powers to increase to the point that the person can't control them anymore. In one instance, Supergirl was overwhelmed by the increase of her power levels under the planet Rann's three yellow suns.
On a much narrower scale, it's possible to overwhelm a Kryptonian by targeting a specific sense, as all of their senses are magnified to a fault.
Hearing: Kryptonians are able to both hear everything at once out to a certain distance, and pick the quietest sound out of a cacophony. While properly trained Kryptonians have no trouble filtering out all the background noise when a situation calls for it, as well as in order to live a normal day-to-day life, an untrained Kryptonian ear might be easily overwhelmed by too much noise. For the trained ear, an overload of many different noises could temporarily throw the Kryptonian off-kilter, rendering him or her either stunned or unable to detect something specific, such as a bomb timer or the approach of another attacker.
Also, any specific sound, at enough decibels, could be painful to sensitive Kryptonian ears, and if it's loud enough, there's the chance an eardrum could be ruptured. Superman has been overwhelmed by specific pitches at high decibels on several occasions, most recently by Black Canary's 'Canary Cry' on Smallville, and also notably, in Superman: the Movie, when Lex Luthor used ultra-high frequencies to communicate with him. Other characters with control over sonics that could be used in this fashion include Silver Banshee (with a sonic death wail), Pied Piper (former Flash rogue with a sonic flute), Temblor (The Batman), Sonar (an occasional rogue of the Green Lantern Corps), and Shriek (Batman Beyond).
Sight: Kryptonian eyes, being highly sensitive to all frequencies of light, could potentially be overwhelmed by intensely bright light. While a Kryptonian has no trouble flying through a sun without being blinded, it's possible that even brighter light could do at least temporary damage to his or her retinas. Also, an intensely bright light that the Kryptonian is not expecting (especially if his or her eyes are adjusted for low light levels) could be painful and briefly blinding. Other aspects of Kryptonian vision (X-ray, heat, microscopic, telescopic) may or may not be affected, but it is possible that a temporarily blinding light could disrupt any of these abilities for a short time. One notable villain that could manipulate light to these purposes is Dr. Light, an occasional enemy of the Justice League and the Teen Titans.
Internal Attacks
Microorganisms:
One commonly held misconception is that Superman can't get sick. To the contrary, this is one area that a Kryptonian might be fairly vulnerable. Indeed, despite having a fairly resilient immune system, Clark has been known to catch a cold on occasion. In one recent instance on Smallville, he discovered his super breath after a sneeze brought on by a cold. Overall, it's unknown how deadly a virus, bacteria, or parasite would have to be to get past a Kryptonian immune system, or how sick that person might become, but I don't know of any instances when a Kryptonian has become deathly ill from a natural, Earth-borne microorganism.
Indeed, some of the worst instances of Kryptonian illness have occurred as a result of kryptonite poisoning (Lois & Clark) and other forms of radiation (Superman IV - Clark developed radiation sickness from scratches made by Nuclear Man). If a microorganism were to be altered in such a way as to include kryptonite or some other harmful substance, it's quite possible that such an attack could easily kill a Kryptonian.
Pharmaceuticals and Other Drugs:
Under normal conditions, pharmaceuticals and other toxic agents (poisons or specialized gases such as Scarecrow's fear toxin) might not have the same full effects on Kryptonians that they do on humans, but they do affect them. Clark has been drugged in some way on many occasions. Of course, some camps claim that Kryptonians are nearly resistant to practically all drugs and toxins, while other camps hold that they are quite susceptible to them. In either case, it's generally accepted that Kryptonians feel little to no effects from both caffeine and alcohol.
Mind Control:
This is one area where Kryptonians are practically wide open to attack. Whether the attack is of the biological or psychic variety, Kryptonians have little hope to retain control of themselves when their minds are being driven from an outside source. As with magic, Superman has been used to inflict a great deal of damage and injury this way.
In the biological arena, a Kryptonian might be susceptible to any of Poison Ivy's specially bred plant spores or other biological toxins. There are several canon instances wherein Superman was controlled by her mind-control spores, including one instance on The Batman, when he was mind-controlled by such spores that had been laced with kryptonite in order to have a more full effect. As the perennial favorite of fans, Ivy's fanon-centric 'sex pollen' is thought to have a similar level of affect on Kryptonians, rendering them unable to resist their sexual desires, or desiring of sex to the point where they cannot control themselves.
Psychically, as with magic, a Kryptonian has little defense, especially if they do not know an attack is coming, or do not recognize it for what it is. Superman has been mind controlled by the likes of Starro, the Black Mercy (a 'wish-fulfilling' parasitic plant; Justice League Unlimited), and Eclipso (mind control was achieved via demonic possession), and he has even been hypnotized (Lois & Clark; under hypnosis, Clark told Lois his Kryptonian name).
Otherwise, Kryptonians are generally resistant to telepathic attacks and erstwhile contact (as asserted by J'onn Jonzz, the Justice League's Martian telepath), and when under psychic attacks of any sort, may be able to reassert themselves to a degree if they know what is happening to them, or if they have help from an outside source. The incident with the Black Mercy required Batman and Wonder Woman's outside influence to help Superman shake off the illusion.
The Phantom Zone
Though this isn't usually considered to be a weakness, Kryptonians are very much affected by the different physics of the Phantom Zone. Discovered by Jor-El and used a prison, the Zone is an alternate dimension, wherein Kryptonians are powerless, exist as wraiths, and can observe the outside world without being able to influence it. Kryptonians become telepathic with one another while in the Zone, and neither age (with the exception of Lor-Zod/Chris Kent, who was born there) nor require sustenance. If a Kryptonian is hit by the Phantom Zone projector and thusly imprisoned, there is no way for him or her to escape.
The Zone has been portrayed as a flat shard of crystal (Superman movieverse), a broad, craggy plain (Smallville and Supergirl), and an endless void (DCAU), and it is usually reachable through the Phantom Zone projector, which is stored in the Fortress of Solitude.
Criminals that have been imprisoned in the Zone include General Zod, Ursa, Non, and Jax-Ur. Other non-Kryptonians have been imprisoned there as well, both on purpose and by accident, including Guy Gardner and Bruce Wayne.
Kryptonians, Daxamites, and Notable Exceptions to the Rules
So, now you know how to hurt a Kryptonian, but just who can you torture with this knowledge? You'll be surprised just how many Kryptonians and Kryptonian relatives there are out there just waiting to be smacked with a piece of kryptonite, dusted with Ivy's spores, or have their ear drums blown out!
Kal-El/Clark Kent/Superman: all canon; fully powered Kryptonian with all the classic weaknesses.
Kara Zor-El/Kara Kent/Supergirl: comics, movieverse, and Smallville; Kal-El's cousin; fully powered Kryptonian; Synthetic Green Kryptonite may have less effect on her than on other Kryptonians.
Kon-El/Conner Kent/Superboy: comics only; partially human clone of Kal-El, containing DNA from Lex Luthor; his tactile telekinesis (TTK), which is an energy field that he can manipulate, is responsible for his powers and his invulnerability. Before his Kryptonian powers fully manifested, his TTK was not quite strong enough to withstand high powered energy blasts, fire, heat, or some gaseous and liquid based attacks.
Kara Zor-L/Karen Starr/Power Girl: comics only; Kal-El's cousin from a now alternate universe (Earth 2); currently fully powered Kryptonian, only occasionally vulnerable to K. For a time her powers and power levels fluctuated, and one time she was vulnerable to weapons made from natural elements, like wood.
Kal-L/Clark Kent/Superman: comics only; Golden Age Superman, from a now alternate universe (Earth 2); fully powered Kryptonian; invulnerable to Kryptonite; died in the Infinite Crisis storyline.
Superboy Prime/Superman Prime (Kal-El/Clark Kent): comics only; Superboy from an alternate universe (Earth Prime/possibly Earth 51 after Countdown to Infinite Crisis); fully powered Kryptonian at the same power levels as the Silver Age Superman; he is invulnerable to Kryptonite, and highly resistant to magic. His power suit grants him an even higher power level by exposing him to intense yellow solar radiation, but since he is highly dependent on this radiation, removing his suit and/or exposing him to red solar radiation will diminish his power level.
Lara Lor-Van: all canon; mother of Kal-El, Kryptonian scientist killed during the destruction of Krypton.
Jor-El: all canon; father of Kal-El, Kryptonian scientist killed during the destruction of Krypton.
Zor-El: comics, movieverse, Smallville, DCAU; brother of Jor-El, father of Kara Zor-El, Kryptonian scientist killed during the destruction of Krypton.
General Dru-Zod: comics, movieverse, DCAU, Smallville; fully powered Kryptonian general imprisoned in the Phantom Zone for attempting to overthrow Krypton's Science Council; father of Lor-Zod (comics) and/or Drax (Legion of Superheroes); his powers were removed at the end of the Lester cut of Superman II.
Ursa/Faora Hu-Ul/Mala: comics, movieverse, DCAU; man-hating, fully powered Kryptonian loyal to General Dru-Zod and imprisoned in the Phantom Zone alongside him, known as Faora in Pre-crisis comics, as Mala in Superman: The Animated Series, and as Ursa in the first two Superman films; mother of Lor-Zod (comics) and/or Drax (Legion of Superheroes); her powers were removed at the end of the Lester cut of Superman II.
Non: comics, movieverse; fully powered Kryptonian, a seemingly non-verbal brute loyal to General Dru-Zod and imprisoned in the Phantom Zone alongside him; in comics canon he was a friend to Jor-El and a member of the Kryptonian Science Council, before leading a separatist movement, then being kidnapped and possibly lobotomized, transforming him into the mute brute known from the Superman movieverse; his powers were removed at the end of the Lester cut of Superman II, and it is thought that he fell to his death shortly thereafter, while a cut clip showed him, Zod, and Ursa being arrested and led away in police cars.
Lor-Zod/Chris Kent: comics only; son of General Dru-Zod and Ursa, he was conceived and born in the Phantom Zone, and later arrived on Earth via a spaceship similar to the one Kal-El arrived in; after being examined, he was taken in by Clark Kent and Lois Lane as a foster son; his powers are still developing, but it appears that he will grow into a fully powered Kryptonian.
Jax-Ur: comics and DCAU; fully powered Kryptonian imprisoned in the Phantom Zone for the destruction of one of Krypton's moons; during the Silver Age, he was occasionally shown as a compatriot of Zod and Faora; on Superman: The Animated Series he was portrayed similar to General Zod, and Mala was his co-conspirator and possible lover.
Karsta Wor-Ul/Kristin Wells: comics only; fully powered Kryptonian who was one of a handful of Kryptonian soldiers to escape the planet's destruction by defecting from the interstellar navy; Pre-crisis, Kristin Wells was a human from the 29th century, who traveled back to our time and became Superwoman, with powers based on technology from the future.
Zara, Ching, Lord Nor: Lois and Clark only; fully powered Kryptonians from the colony planet, New Krypton; Zara had been betrothed to Kal-El before the destruction of Krypton, but after their relationship was dissolved, she took Ching as her husband; Lord Nor was their enemy.
Kell-El/Superman X: Legion of Superheroes only; a fully powered clone of Kal-El bred in the 41st century to be invulnerable to K, and to fight the intergalactic dictator, Imperiex; he also possesses energy-based powers that allow him to produce a beam from his hand that encases its target in green crystal, project an energy shield from the S-shield on his uniform, and project blade-like weapons from the backs of his gloves.
Galatea: Justice League Unlimited only; fully powered, more mature clone of Supergirl bred by Dr. Emil Hamilton and Project Cadmus; she shared a psychic link with Supergirl, and had been brain-washed/trained to believe the League were her enemies; her character was physically similar to Power Girl.
Raya: Smallville only; Kryptonian scientist who worked with Jor-El and helped build Kal-El's ship; was sent into the Phantom Zone by Jor-El to save her from Krypton's destruction; nearly fully powered after she was freed from the Phantom Zone; she was killed by a human possessed by a phantom from the Zone.
Dax-Ur: Smallville only; Kryptonian scientist who came to Earth many years earlier (before Krypton's destruction); used blue kryptonite to block his powers in order to live a normal life, and had a wife and a half-human son, Max (whose abilities are unknown); may have been a relative of Jax-Ur; he was killed by Brainiac in the episode “Persona”.
Jason White: Superman Returns only; Kal-El's son with Lois Lane, he is half-human; the extent of abilities and weaknesses is unknown, but at age five he has already displayed superhuman strength and a potential immunity to kryptonite.
Legion of Super-Pets: comics, DCAU; partially or fully powered animals either from Krypton or possessing Kryptonian powers; Krypto is Kal-El's dog, formerly the family dog of the House of El, and while he used to “hate everybody” in the comics, he has calmed down in recent comics, and is always fiercely loyal to Kal-El and other members of the El family; his sensory powers may exceed those of Kryptonians; Streaky is Supergirl's Terran cat, who in pre-crisis comics gained powers from an exposure to X-kryptonite; Comet the Superhorse was Supergirl's horse in pre-crisis comics; he is unaffected by kryptonite or red solar radiation, and his story is simply too bizarre to fit into this description! Beppo is a monkey (similar to a chimp) from Krypton, and possesses traditional Kryptonian powers.
Kandorians: comics, DCAU; Kandor was a Kryptonian city that was stolen and miniaturized by Brainiac, and is currently under Kal-El's possession in the Fortress of Solitude; all Kandorians are normal Kryptonians, who live beneath an artificial red sun within the bottle city; on one occasion when their red sun was replaced by a yellow sun, they gained abilities identical to Kal-El's (Legion of Superheroes); Kal-El has been worshipped as a god by Kandorians due to a difference in time passage, and Supergirl and Power Girl recently spent time living in Kandor and masquerading as the Kryptonian heroes Nightwing and Flamebird; Kandor has recently been under the rule of Ultraman, an evil alternate version of Superman from another reality.
Daxamites: comics only; an off-shoot race from Kryptonians, they split off long ago, settled on the planet Daxam, and became a severely xenophobic and religiously intolerant race; similarly powered to Kryptonians, but with no weakness to kryptonite, and an additional deadly vulnerability to lead, even in small amounts.
Lar Gand/Valor/Mon-El: comics only; Daxamite; he crash-landed in Smallville when Kal-El was Superboy, suffering from partial amnesia, and Clark gave him the name Mon-El, thinking he might have been a long lost brother; after an accidental exposure to lead, he remembered his origin, and Clark saved him by sending him into the Phantom Zone, where he remained for over a thousand years.
Sodam Yat: comics only; Daxamite; a member of the Green Lantern Corps, who was granted the vastly powerful Ion symbiote in order to fight Superman Prime; after a lethal exposure to lead during that fight, he has to retain the Ion symbiote and wear his fully-charged power ring at all times in order to avoid succumbing to the poisoning.
Bizarro: comics, DCAU, Smallville; a clone of Superman made by Lex Luthor, who possesses reverse powers of Kryptonians, such as freeze-vision and heat-breath; he is weakened by blue kryptonite and yellow sunlight, but other vulnerabilities should be the same as those of Kryptonians.
This list could go on for many pages, indeed. A more complete list of Kryptonians can be found on Wikipedia.
Conclusion and Resources
If you're still reading this, I'm sure your eyes have long since crossed and glazed over. Congratulations for reaching the end! I hope you've enjoyed exploring the dark side of what it means to be Kryptonian as much as I have. Clearly, they're not nearly as invulnerable as the hype would have us believe. Now go forth, and torture some Kryptonians!
Resources
This is by no means a complete list, but it should serve as a starting point for more information.
Alan Kistler on Superman's Weaknesses: an essay outlining the basics of Kryptonian weaknesses.
Kryptonite: essay about the mineral (Wikipedia)
How Kryptonite Works: essay on the mineral (How Stuff Works)
Kryptonians: an essay about the race (Wikipedia)
Phantom Zone: an essay on the Phantom Zone (Wikipedia)
Alternate Versions of Superman: an article listing all of the different versions of Superman that have appeared over the years (Wikipedia)
or
Gentlemen, how do we kill Superman?
In my essay, Writing Clark Kent, I discussed the myriad powers he possesses. But what about his weaknesses? Here, we'll look at all the things that can hurt the average Kryptonian, including the many forms of kryptonite.
There are seven categories of Kryptonian weaknesses:
1. Kryptonite
2. Magic
3. Red solar radiation
4. Exhausted power reserves and overwhelming force
5. Overloaded powers
6. Internal attacks (viruses and other disease, mind control)
7. The Phantom Zone
Kryptonite
The perennial favorite of villains everywhere, kryptonite has been used as a foil for Superman ever since the early days of the radio show, when it was created in order to give the voice actor, Bud Collyer, a day off of work. First appearing in pre-Crisis comics as a green crystal, it was later joined by a red variety, and eventually, the group of kryptonite varieties expanded to include nearly the entire rainbow, as well as forms such as Kryptonite-X and Slow Kryptonite.
Origins and Science
Most forms of kryptonite were once part of the core of the planet Krypton. When Krypton was destroyed, its core (and possibly the entire crust as well) was irradiated in such a way the minerals were transformed into a radioactive form that is capable of killing Kryptonians. This was the original Green Kryptonite. In pre-Crisis comics, Red Kryptonite was created when large quantities of green kryptonite passed through a cloud of unknown gases in space as it followed the trajectory the infant Kal-El's spaceship took to reach Earth. Post-Crisis, Red K was first made by Mr. Mxyzptlk, then created synthetically by Ra's al Ghul.
Other forms have been created from green kryptonite through various means, including heating, laboratory experiments, magical transformation, and possibly exposure to other elements in space. A few varieties are completely man-made.
The composition of kryptonite has been speculated to be everything from a stable transuranic element with the atomic number 126 and a half-life of 250,000 years, to the complex crystal molecule 'lithium boron silicate hydroxide with fluorine', as seen in Superman Returns. In any case, it has nothing to do with the element Krypton, which is a noble gas that does not usually bond with any other element, and is used in some light bulbs.
But what does kryptonite do? Well, in its original form (Green), it is speculated that the radiation disrupts the cellular processes that are responsible for a Kryptonian's strength and other powers. It drives the stored energy out of the cells entirely (essentially destroying the energy-laden bonds within certain molecules), leaving the Kryptonian weak, powerless, and sick. After long or intense exposure, the result is death.
Kryptonite does also affect other beings, since it is a radioactive substance. The result of a long exposure is radiation sickness, as evidenced by Lex Luthor's bout with cancer and the subsequent loss of one of his hands in the comics.
In all canon, all forms of kryptonite radiation can be blocked by lead.
Varieties
Green Kryptonite
Canon: All canon
Effects: Robs any super-powered Kryptonian of their powers, makes them weak and sick, including causing severe pain and nausea, and giving a green tinting to the skin and irises. Exposure leaves the Kryptonian vulnerable to injury, and prolonged exposure leads to death. In some current comics it does not rob the affected Kryptonian of their powers immediately, but leaves them sick and in severe pain.
In Smallville, Green Kryptonite can mutate human DNA, granting a wide variety of powers as well as potentially leaving the affected person mentally unstable and prone to violence.
Red Kryptonite
Canon: Comics, Smallville, Super Friends, Lois and Clark, Krypto the Superdog
Effects: In the comics, the effects of Red K vary from one exposure to the next. It may cause anything from lowered inhibitions to anger to apathy to growing a third eye.
From Wikipedia:
“Superman has suffered the following random effects upon exposure to various pieces of red kryptonite: being turned into a dragon, a non-powered giant, a dwarf, an ant-headed humanoid, a lunatic, and an amnesiac; being made unable to see anything colored green; growing incredibly long hair, nails, and beard; being rendered totally powerless; growing fat; gaining the ability to read thoughts; growing a third eye in the back of his head; losing his invulnerability along the left side of his body; being split into an evil Superman and a good Clark Kent; being split into young and old forms (Superboy and Superman); being rendered unable to speak or write anything but Kryptonese; growing an extra set of arms; becoming clumsy; swapping bodies with the person nearest him upon exposure to it; transferring his powers; rapidly aging; multiple personality changes; and having his skin rendered transparent, overloading him with solar power.”
In Smallville canon, Red K only works upon contact with skin, and induces a drug-like effect, resulting in the loss of inhibitions, unpredictability, and general selfishness and eroticism. It has the same effect with every exposure, and the effects last as long as close contact with the mineral is maintained.
Outside of Smallville, the effects of Red K generally last 24-48 hours, after which the affected Kryptonian will be immune to that particular piece of Red K.
Blue Kryptonite
Canon: Comics, Super Friends, DCU video games, Smallville
Effects: In the comics, Blue K was created by the same duplicator ray that created Bizarro. In pre-Crisis comics, Blue K hurts Bizarro in the same way that Green K hurts Kryptonians. Post-Crisis, it also makes Bizarro kind and intelligent. Blue K was used to heal Superman from the effects of Red K in one episode of Super Friends, and has been used as a general life restorative on Kryptonians in several video games.
In Smallville, Blue K suppresses Kryptonian super powers and removes the sensitivity to Green K. It also increases Bizarro's powers exponentially.
Gold Kryptonite
Canon: Comics, Super Friends
Effects: Permanently robs the effected Kryptonian of their powers by destroying the cellular machinery responsible for them. Does not cause sickness!
Black Kryptonite
Canon: Comics, Smallville, Superman III
Effects: Originally seen in Smallville, created by super-heating Green K, this variety can split a person (or plants, even) into two distinct beings, one 'good' and one 'bad'. It can also be used to reunite those split halves. It is unclear whether or not Black K can split a Kryptonian fully in two, here (full discussion of the subject is here, if you'd like to break your brain). In the comics, Black K was synthetically created by Darkseid, and can separate a Kryptonian into two distinct beings, along the same lines as the Smallville variety (it was used to split Supergirl into a 'good' version and a 'bad' version, which were fused again by Diana's Golden Lasso). Finally, in All-Star Superman, an AU comic, Black K makes Superman evil.
It's interesting to note that in Superman III, a synthesized version of Green K, containing tar in the place of an unknown element, has a similar effect on Superman, splitting him into two people, one 'good' and one 'bad', after first acting like Red K, making him apathetic, angry, and somewhat violent.
White Kryptonite
Canon: Comics only
Effects: Formed from Green K that passed through a 'cosmic cloud', White K destroys all plant life, whether Kryptonian or not. In one comic, possibly an Elseworlds title, Superman used a small piece of White K to counter the effects of Gold K. This effect only lasted as long as close contact was maintained with the mineral.
Jewel Kryptonite
Canon: Comics only
Effects: Formed from the Jewel Mountains on Krypton, Jewel K amplifies the psychic powers of Phantom Zone residents, permitting them to project illusions into the real world or perform mind-control.
Silver Kryptonite
Canon: Comics, Smallville
Effects: In a Silver-Age comic, Silver K was a hoax used to celebrate the silver anniversary of the creation of “Superman”. In Superman/Batman #46, Silver K was the name initially given to a form of kryptonite that had been magically altered to enslave the mind of the affected person in an escapist fantasy. A version of Silver K in Smallville gave Clark paranoid delusions, but this was also a hoax, as the mineral turned out to be a part of Brainiac.
Magic Kryptonite
Canon: Comics only
Effects: This is the newest addition to the many varieties of K. Originally referred to as Silver Kryptonite, Magic K is actually only two magically enchanted pieces of Kryptonite, one shaped like a crescent moon, and the other its compliment, creating a complete disc when put together. Called the “Ach-Om-Rashay”, or the Amulet of Mindfulness, the pieces (when only one is present) put a spell of mind control, or enslavement, on any person that comes in close contact with them, causing the person to either see or live out an escapist fantasy. In Clark's case, it made him completely care-free, seeming to be 'high'. The spell is countered by exposing the affected person to the other piece. In the comics, the crescent shaped piece was supposedly destroyed by being thrown into the sun, but both were shown later as part of a secret collection in the Bat Cave.
Pink Kryptonite (the perennial favorite with fans! ^_~)
Canon: Comics AU, fanon
Effects: Shown in only one panel in an AU Supergirl storyline by Peter David, Pink K turns heterosexual Kryptonians temporarily and stereotypically gay. It is unknown whether or not the effect works in reverse.
Amber Kryptonite
Canon: Fanon only
Effects: Introduced in quirky_circe's 20 Random Things About Kal-El, Amber K makes the affected Kryptonian “blind stinking drunk”.
Lavender Kryptonite
Canon: Fanon only
Effects: Introduced in ljs_lj's Lavender, Lavender K temporarily changes the sex (and all associated physical features) of the affected Kryptonian.
Other rare forms of kryptonite include Anti-Kryptonite, X-Kryptonite, Slow Kryptonite, Magno-Kryptonite, Bizarro Kryptonite, and Kryptonite X/Kryptisium. None of these forms have any effect on Kryptonians (except for Anti-Kryptonite, which works like Green K on non-super-powered Kryptonians).
Hoaxes include Yellow Kryptonite, 2 forms of Silver Kryptonite, Blood Kryptonite (used by the Cult of Connor in the “52” storyline), Kryptonite Plus, Purple Spotted Kryptonite (which made Krypto chase his tail in Krypto the Superdog), and Fake Kryptonite.
Magic
By far, a Kryptonian's greatest weakness is magic. They are simply completely vulnerable to its whims. The effects don't necessarily include loss of powers or sickness, as the field involved in a magical spell disrupts any defenses the Kryptonian might have, but they can include anything and everything if the spell intends it. On many occasions, Superman has been affected, hurt, or used as a weapon himself under the influence of magic. Considering the potential for trouble when magic is involved, Clark is understandably wary of magic and magic users.
Notable Magic Users
Dr. Fate: Any of a number of people who have worn both the Helm of Nabu, which is possessed by the spirit of the ancient wizard Nabu, and the Amulet of Anubis, which confers vast magical abilities. Dr. Fate is a powerful sorcerer, and has occasionally been an ally to both the Justice Society and the Justice League.
Eclipso: Any of a number of people that have been possessed by the vengeance demon, Eclipso, via a black diamond (of which there are several). Eclipso's magical abilities are generally limited to possession and powers of persuasion/influence.
Felix Faust: A power-hungry master sorcerer with no good intentions. He's often a thorn in the Justice League's side.
Jason Blood: An occasional ally of Batman, he is an adept magic user who is sometimes called in to help with occult matters. As he is bound to the Demon Etrigan (who is a powerful magic user himself and also speaks in rhyme), the two share the same body and occasionally shift from one form to the other.
Mary Marvel: The alter-ego of Mary Batson, she recently came into great magical powers when she absorbed some of Black Adam's power. Under that dark influence, she 'studied' under Zatanna, Eclipso, Klarion the witch boy, and Granny Goodness, increasing her powers and her propensity for evil. Currently, she's working for Darkseid in 'Final Crisis'.
Morgaine le Fey: The ancient, diabolical sorceress of Arthurian legend, she's been an enemy of the Demon Etrigan since Arthurian times. She's immortal, and is a master of vastly powerful black magic, which she uses without restraint.
Mr. Mxyzptlk: Often called Mxy, he is an imp from the Fifth Dimension who tends to use his seemingly unlimited powers to simply cause Superman trouble. The only way to send him back to his home dimension and counter his spells is to trick him into saying his name backwards (Kltpzyxm).
Phantom Stranger: An occasional ally of the Justice League, he is literally a mysterious stranger with unclear origins, who possesses magical abilities with undetermined limits.
The Spectre: A cosmic entity that is best known for being the avenging hand of God, the Spectre is usually bound to a human host. He possesses seeming omnipotence, but does not ally himself with anyone or choose sides. For a time, the Spectre inhabited Hal Jordan.
Zatanna: As the Justice League's usual resident magician, she often has to counter nefarious magical attacks and spells. She speaks all her spells in reverse, and one often quoted panel depicts her shouting the spell, “NAMREPUS, POTS!!” telling Superman to stop what he's doing. Her teen-aged cousin, Zachary, is a similarly powered magician (without the ability to affect humans with his spells) who was at one time a Teen Titan.
Other magic users include Klarion the witch boy, the demon prince Neron, Raven, the wizard Shazam, and Traci Thirteen.
Red Solar Radiation
Kryptonians aren't susceptible to radiation as we think of it, however, the radiation of a red sun (light in the red end of the spectrum) has the potential to weaken Kryptonians by supposedly locking up the cellular machinery responsible for super-human abilities so they can't process the stored energy. This would have the physical effect of rendering the Kryptonian powerless until such a time that the red solar radiation is replaced with yellow.
Some sources have hypothesized that red sun radiation drives the stored energy out of the cells, however, other sources believe that the Kryptonian's loss of powers under the influence of red wavelengths is the result of the gradual withdrawal of yellow wavelengths, of the Kryptonian using up his or her energy reserves and not being able to replenish them. If the former is the case, then the affected Kryptonian will lose his or her powers rapidly. If the latter is true, then the power loss is slow and gradual. With the latter also comes the possibility that under an orange sun, a Kryptonian would retain some of his or her abilities at a diminished level.
Following the events of Infinite Crisis, at the end of which Superman flew through a red sun, Clark was powerless for an entire year. This lends some credence to the theory that red solar radiation drives the stored energy out, though it was also thought that his prolonged power loss was more due to a psychological block.
However it works, the end result of this is that villains have often used red solar radiation in some form as a weapon against Superman and other Kryptonians, even devising prison cells with red solar lamps to keep Superman powerless and incapable of escape.
Exhausted Power Reserves and Overwhelming Force
Contrary to some opinions, Superman's power is not limitless. That goes for every other Kryptonian as well. At some point in a prolonged fight against an extremely powerful opponent or many less powerful opponents, the Kryptonian will begin to tire, all that stored energy used up with no opportunity to recharge. This is the same phenomenon we know as humans: when you run out of energy, you simply can't fight any longer.
The same goes for when a Kryptonian fights a more powerful opponent. They can be overpowered by simple force, and it has happened on many occasions.
Notably powerful people include any of the Green Lanterns, any of the Marvel family, Wonder Woman, Darkseid (the tyrannical ruler of the planet Apokolips), Doomsday (the genetically engineered monster who fought Superman seemingly to the death), Mongul (the tyrannical ruler of Warworld), and Superboy Prime (an alternate dimension Superboy, who has recently grown into Superman Prime).
In addition, weapons with enough energy to inflict damage to the bioelectric 'aura' protecting the Kryptonian could weaken or injure that Kryptonian. A single lightening bolt wouldn't be enough to hurt, but the power of several city blocks once left Superman in severe pain, and he was once knocked out by the blast of a 90 megaton bomb. In one instance on Superman: The Animated Series, he was hurt by extreme amounts of electrical current directed at him by Livewire.
Overloaded Powers
At the opposite end of the spectrum, it's possible to overload a Kryptonian's powers. On a broad scale, too much yellow sun radiation can cause a Kryptonian's powers to increase to the point that the person can't control them anymore. In one instance, Supergirl was overwhelmed by the increase of her power levels under the planet Rann's three yellow suns.
On a much narrower scale, it's possible to overwhelm a Kryptonian by targeting a specific sense, as all of their senses are magnified to a fault.
Hearing: Kryptonians are able to both hear everything at once out to a certain distance, and pick the quietest sound out of a cacophony. While properly trained Kryptonians have no trouble filtering out all the background noise when a situation calls for it, as well as in order to live a normal day-to-day life, an untrained Kryptonian ear might be easily overwhelmed by too much noise. For the trained ear, an overload of many different noises could temporarily throw the Kryptonian off-kilter, rendering him or her either stunned or unable to detect something specific, such as a bomb timer or the approach of another attacker.
Also, any specific sound, at enough decibels, could be painful to sensitive Kryptonian ears, and if it's loud enough, there's the chance an eardrum could be ruptured. Superman has been overwhelmed by specific pitches at high decibels on several occasions, most recently by Black Canary's 'Canary Cry' on Smallville, and also notably, in Superman: the Movie, when Lex Luthor used ultra-high frequencies to communicate with him. Other characters with control over sonics that could be used in this fashion include Silver Banshee (with a sonic death wail), Pied Piper (former Flash rogue with a sonic flute), Temblor (The Batman), Sonar (an occasional rogue of the Green Lantern Corps), and Shriek (Batman Beyond).
Sight: Kryptonian eyes, being highly sensitive to all frequencies of light, could potentially be overwhelmed by intensely bright light. While a Kryptonian has no trouble flying through a sun without being blinded, it's possible that even brighter light could do at least temporary damage to his or her retinas. Also, an intensely bright light that the Kryptonian is not expecting (especially if his or her eyes are adjusted for low light levels) could be painful and briefly blinding. Other aspects of Kryptonian vision (X-ray, heat, microscopic, telescopic) may or may not be affected, but it is possible that a temporarily blinding light could disrupt any of these abilities for a short time. One notable villain that could manipulate light to these purposes is Dr. Light, an occasional enemy of the Justice League and the Teen Titans.
Internal Attacks
Microorganisms:
One commonly held misconception is that Superman can't get sick. To the contrary, this is one area that a Kryptonian might be fairly vulnerable. Indeed, despite having a fairly resilient immune system, Clark has been known to catch a cold on occasion. In one recent instance on Smallville, he discovered his super breath after a sneeze brought on by a cold. Overall, it's unknown how deadly a virus, bacteria, or parasite would have to be to get past a Kryptonian immune system, or how sick that person might become, but I don't know of any instances when a Kryptonian has become deathly ill from a natural, Earth-borne microorganism.
Indeed, some of the worst instances of Kryptonian illness have occurred as a result of kryptonite poisoning (Lois & Clark) and other forms of radiation (Superman IV - Clark developed radiation sickness from scratches made by Nuclear Man). If a microorganism were to be altered in such a way as to include kryptonite or some other harmful substance, it's quite possible that such an attack could easily kill a Kryptonian.
Pharmaceuticals and Other Drugs:
Under normal conditions, pharmaceuticals and other toxic agents (poisons or specialized gases such as Scarecrow's fear toxin) might not have the same full effects on Kryptonians that they do on humans, but they do affect them. Clark has been drugged in some way on many occasions. Of course, some camps claim that Kryptonians are nearly resistant to practically all drugs and toxins, while other camps hold that they are quite susceptible to them. In either case, it's generally accepted that Kryptonians feel little to no effects from both caffeine and alcohol.
Mind Control:
This is one area where Kryptonians are practically wide open to attack. Whether the attack is of the biological or psychic variety, Kryptonians have little hope to retain control of themselves when their minds are being driven from an outside source. As with magic, Superman has been used to inflict a great deal of damage and injury this way.
In the biological arena, a Kryptonian might be susceptible to any of Poison Ivy's specially bred plant spores or other biological toxins. There are several canon instances wherein Superman was controlled by her mind-control spores, including one instance on The Batman, when he was mind-controlled by such spores that had been laced with kryptonite in order to have a more full effect. As the perennial favorite of fans, Ivy's fanon-centric 'sex pollen' is thought to have a similar level of affect on Kryptonians, rendering them unable to resist their sexual desires, or desiring of sex to the point where they cannot control themselves.
Psychically, as with magic, a Kryptonian has little defense, especially if they do not know an attack is coming, or do not recognize it for what it is. Superman has been mind controlled by the likes of Starro, the Black Mercy (a 'wish-fulfilling' parasitic plant; Justice League Unlimited), and Eclipso (mind control was achieved via demonic possession), and he has even been hypnotized (Lois & Clark; under hypnosis, Clark told Lois his Kryptonian name).
Otherwise, Kryptonians are generally resistant to telepathic attacks and erstwhile contact (as asserted by J'onn Jonzz, the Justice League's Martian telepath), and when under psychic attacks of any sort, may be able to reassert themselves to a degree if they know what is happening to them, or if they have help from an outside source. The incident with the Black Mercy required Batman and Wonder Woman's outside influence to help Superman shake off the illusion.
The Phantom Zone
Though this isn't usually considered to be a weakness, Kryptonians are very much affected by the different physics of the Phantom Zone. Discovered by Jor-El and used a prison, the Zone is an alternate dimension, wherein Kryptonians are powerless, exist as wraiths, and can observe the outside world without being able to influence it. Kryptonians become telepathic with one another while in the Zone, and neither age (with the exception of Lor-Zod/Chris Kent, who was born there) nor require sustenance. If a Kryptonian is hit by the Phantom Zone projector and thusly imprisoned, there is no way for him or her to escape.
The Zone has been portrayed as a flat shard of crystal (Superman movieverse), a broad, craggy plain (Smallville and Supergirl), and an endless void (DCAU), and it is usually reachable through the Phantom Zone projector, which is stored in the Fortress of Solitude.
Criminals that have been imprisoned in the Zone include General Zod, Ursa, Non, and Jax-Ur. Other non-Kryptonians have been imprisoned there as well, both on purpose and by accident, including Guy Gardner and Bruce Wayne.
Kryptonians, Daxamites, and Notable Exceptions to the Rules
So, now you know how to hurt a Kryptonian, but just who can you torture with this knowledge? You'll be surprised just how many Kryptonians and Kryptonian relatives there are out there just waiting to be smacked with a piece of kryptonite, dusted with Ivy's spores, or have their ear drums blown out!
Kal-El/Clark Kent/Superman: all canon; fully powered Kryptonian with all the classic weaknesses.
Kara Zor-El/Kara Kent/Supergirl: comics, movieverse, and Smallville; Kal-El's cousin; fully powered Kryptonian; Synthetic Green Kryptonite may have less effect on her than on other Kryptonians.
Kon-El/Conner Kent/Superboy: comics only; partially human clone of Kal-El, containing DNA from Lex Luthor; his tactile telekinesis (TTK), which is an energy field that he can manipulate, is responsible for his powers and his invulnerability. Before his Kryptonian powers fully manifested, his TTK was not quite strong enough to withstand high powered energy blasts, fire, heat, or some gaseous and liquid based attacks.
Kara Zor-L/Karen Starr/Power Girl: comics only; Kal-El's cousin from a now alternate universe (Earth 2); currently fully powered Kryptonian, only occasionally vulnerable to K. For a time her powers and power levels fluctuated, and one time she was vulnerable to weapons made from natural elements, like wood.
Kal-L/Clark Kent/Superman: comics only; Golden Age Superman, from a now alternate universe (Earth 2); fully powered Kryptonian; invulnerable to Kryptonite; died in the Infinite Crisis storyline.
Superboy Prime/Superman Prime (Kal-El/Clark Kent): comics only; Superboy from an alternate universe (Earth Prime/possibly Earth 51 after Countdown to Infinite Crisis); fully powered Kryptonian at the same power levels as the Silver Age Superman; he is invulnerable to Kryptonite, and highly resistant to magic. His power suit grants him an even higher power level by exposing him to intense yellow solar radiation, but since he is highly dependent on this radiation, removing his suit and/or exposing him to red solar radiation will diminish his power level.
Lara Lor-Van: all canon; mother of Kal-El, Kryptonian scientist killed during the destruction of Krypton.
Jor-El: all canon; father of Kal-El, Kryptonian scientist killed during the destruction of Krypton.
Zor-El: comics, movieverse, Smallville, DCAU; brother of Jor-El, father of Kara Zor-El, Kryptonian scientist killed during the destruction of Krypton.
General Dru-Zod: comics, movieverse, DCAU, Smallville; fully powered Kryptonian general imprisoned in the Phantom Zone for attempting to overthrow Krypton's Science Council; father of Lor-Zod (comics) and/or Drax (Legion of Superheroes); his powers were removed at the end of the Lester cut of Superman II.
Ursa/Faora Hu-Ul/Mala: comics, movieverse, DCAU; man-hating, fully powered Kryptonian loyal to General Dru-Zod and imprisoned in the Phantom Zone alongside him, known as Faora in Pre-crisis comics, as Mala in Superman: The Animated Series, and as Ursa in the first two Superman films; mother of Lor-Zod (comics) and/or Drax (Legion of Superheroes); her powers were removed at the end of the Lester cut of Superman II.
Non: comics, movieverse; fully powered Kryptonian, a seemingly non-verbal brute loyal to General Dru-Zod and imprisoned in the Phantom Zone alongside him; in comics canon he was a friend to Jor-El and a member of the Kryptonian Science Council, before leading a separatist movement, then being kidnapped and possibly lobotomized, transforming him into the mute brute known from the Superman movieverse; his powers were removed at the end of the Lester cut of Superman II, and it is thought that he fell to his death shortly thereafter, while a cut clip showed him, Zod, and Ursa being arrested and led away in police cars.
Lor-Zod/Chris Kent: comics only; son of General Dru-Zod and Ursa, he was conceived and born in the Phantom Zone, and later arrived on Earth via a spaceship similar to the one Kal-El arrived in; after being examined, he was taken in by Clark Kent and Lois Lane as a foster son; his powers are still developing, but it appears that he will grow into a fully powered Kryptonian.
Jax-Ur: comics and DCAU; fully powered Kryptonian imprisoned in the Phantom Zone for the destruction of one of Krypton's moons; during the Silver Age, he was occasionally shown as a compatriot of Zod and Faora; on Superman: The Animated Series he was portrayed similar to General Zod, and Mala was his co-conspirator and possible lover.
Karsta Wor-Ul/Kristin Wells: comics only; fully powered Kryptonian who was one of a handful of Kryptonian soldiers to escape the planet's destruction by defecting from the interstellar navy; Pre-crisis, Kristin Wells was a human from the 29th century, who traveled back to our time and became Superwoman, with powers based on technology from the future.
Zara, Ching, Lord Nor: Lois and Clark only; fully powered Kryptonians from the colony planet, New Krypton; Zara had been betrothed to Kal-El before the destruction of Krypton, but after their relationship was dissolved, she took Ching as her husband; Lord Nor was their enemy.
Kell-El/Superman X: Legion of Superheroes only; a fully powered clone of Kal-El bred in the 41st century to be invulnerable to K, and to fight the intergalactic dictator, Imperiex; he also possesses energy-based powers that allow him to produce a beam from his hand that encases its target in green crystal, project an energy shield from the S-shield on his uniform, and project blade-like weapons from the backs of his gloves.
Galatea: Justice League Unlimited only; fully powered, more mature clone of Supergirl bred by Dr. Emil Hamilton and Project Cadmus; she shared a psychic link with Supergirl, and had been brain-washed/trained to believe the League were her enemies; her character was physically similar to Power Girl.
Raya: Smallville only; Kryptonian scientist who worked with Jor-El and helped build Kal-El's ship; was sent into the Phantom Zone by Jor-El to save her from Krypton's destruction; nearly fully powered after she was freed from the Phantom Zone; she was killed by a human possessed by a phantom from the Zone.
Dax-Ur: Smallville only; Kryptonian scientist who came to Earth many years earlier (before Krypton's destruction); used blue kryptonite to block his powers in order to live a normal life, and had a wife and a half-human son, Max (whose abilities are unknown); may have been a relative of Jax-Ur; he was killed by Brainiac in the episode “Persona”.
Jason White: Superman Returns only; Kal-El's son with Lois Lane, he is half-human; the extent of abilities and weaknesses is unknown, but at age five he has already displayed superhuman strength and a potential immunity to kryptonite.
Legion of Super-Pets: comics, DCAU; partially or fully powered animals either from Krypton or possessing Kryptonian powers; Krypto is Kal-El's dog, formerly the family dog of the House of El, and while he used to “hate everybody” in the comics, he has calmed down in recent comics, and is always fiercely loyal to Kal-El and other members of the El family; his sensory powers may exceed those of Kryptonians; Streaky is Supergirl's Terran cat, who in pre-crisis comics gained powers from an exposure to X-kryptonite; Comet the Superhorse was Supergirl's horse in pre-crisis comics; he is unaffected by kryptonite or red solar radiation, and his story is simply too bizarre to fit into this description! Beppo is a monkey (similar to a chimp) from Krypton, and possesses traditional Kryptonian powers.
Kandorians: comics, DCAU; Kandor was a Kryptonian city that was stolen and miniaturized by Brainiac, and is currently under Kal-El's possession in the Fortress of Solitude; all Kandorians are normal Kryptonians, who live beneath an artificial red sun within the bottle city; on one occasion when their red sun was replaced by a yellow sun, they gained abilities identical to Kal-El's (Legion of Superheroes); Kal-El has been worshipped as a god by Kandorians due to a difference in time passage, and Supergirl and Power Girl recently spent time living in Kandor and masquerading as the Kryptonian heroes Nightwing and Flamebird; Kandor has recently been under the rule of Ultraman, an evil alternate version of Superman from another reality.
Daxamites: comics only; an off-shoot race from Kryptonians, they split off long ago, settled on the planet Daxam, and became a severely xenophobic and religiously intolerant race; similarly powered to Kryptonians, but with no weakness to kryptonite, and an additional deadly vulnerability to lead, even in small amounts.
Lar Gand/Valor/Mon-El: comics only; Daxamite; he crash-landed in Smallville when Kal-El was Superboy, suffering from partial amnesia, and Clark gave him the name Mon-El, thinking he might have been a long lost brother; after an accidental exposure to lead, he remembered his origin, and Clark saved him by sending him into the Phantom Zone, where he remained for over a thousand years.
Sodam Yat: comics only; Daxamite; a member of the Green Lantern Corps, who was granted the vastly powerful Ion symbiote in order to fight Superman Prime; after a lethal exposure to lead during that fight, he has to retain the Ion symbiote and wear his fully-charged power ring at all times in order to avoid succumbing to the poisoning.
Bizarro: comics, DCAU, Smallville; a clone of Superman made by Lex Luthor, who possesses reverse powers of Kryptonians, such as freeze-vision and heat-breath; he is weakened by blue kryptonite and yellow sunlight, but other vulnerabilities should be the same as those of Kryptonians.
This list could go on for many pages, indeed. A more complete list of Kryptonians can be found on Wikipedia.
Conclusion and Resources
If you're still reading this, I'm sure your eyes have long since crossed and glazed over. Congratulations for reaching the end! I hope you've enjoyed exploring the dark side of what it means to be Kryptonian as much as I have. Clearly, they're not nearly as invulnerable as the hype would have us believe. Now go forth, and torture some Kryptonians!
Resources
This is by no means a complete list, but it should serve as a starting point for more information.
Alan Kistler on Superman's Weaknesses: an essay outlining the basics of Kryptonian weaknesses.
Kryptonite: essay about the mineral (Wikipedia)
How Kryptonite Works: essay on the mineral (How Stuff Works)
Kryptonians: an essay about the race (Wikipedia)
Phantom Zone: an essay on the Phantom Zone (Wikipedia)
Alternate Versions of Superman: an article listing all of the different versions of Superman that have appeared over the years (Wikipedia)