hat tip to dkogan
http://www.reallifecomics.com/ Aug 12, if you use this link later.
I suppose a lot of movies are fan fiction, by that reasoning. But some of my favorite authors do, too. Laurie King, with her Mary Russell books, in particular. Mary Stewart with her Merlin/Arthur series. Lots of others visited that mine. Mary Renault's retelling of old Greek stories.