Mean and Green
They say that black's a villain color. That bad guys wear black, and that good guys wear white. Well, when it comes to superheroes and villains, it often goes differently. When it comes to supervillains, black ain't the main color. Green is. The number of supervillains in Marvel and DC who wear green (or are green in many cases) is staggering. And to prove it, here's a list compiling all of the examples of green supervillains I've found. Note that this is supervillains only, not other villains outside of the superhero genre (such as Boba Fett). Expect more names to be added later.
