Aside from "comic book" (since they're all in that), "superhero" (since most of them are in that), and "action" (since most of them are also in that). If you add any of those three, they will likely be deleted. I thought that categorizing characters by subgenre (sci-fi, fantasy, etc.) would help me (and possibly you) with new fancasts. Characters can be in more than one genre.
