Given the sort of shows I watch the most of, not to mention the general frequency in which animal sidekicks appear in anime, there are many, many possibilities for this entry. So, in the absence of any one long time favorite rising from the recesses of my mind, I’ll go with my recent favorite:
Day 18: Favorite animal side kick, pet, or summoning from any anime
See Also:
Nyanko-sensei, Natsume’s Book of Friends. This is not only because he is voiced by the amazingly-talented Kazuhiko Inoue, it’s also because Nyanko-sensei is just plain fun as a character. First of all, anime cats are always awesome, what with the pwik pwik pwik sfx for their feet and their perfectly expressive catnesses, but Nyanko-sensei is part meat bun, part raging demon - how can you go wrong there?!
Oh, I suppose one could argue Nyanko-sensei is actually neither of these things, but he does seem content to pass himself off as Natsume’s pet - and reap the tasty food benefits that such a station allows - and certainly in his kitty-bun form he is often humorously sidekick-ish. Whatever, he totally counts. ;)
No runners-up right now because uh, there's a lot and anyway I don't have the time. >_>