Being a hero can be a bit dull sometimes. You're always under pressure to do the good and honourable thing and all your friends (those that weren't chopped up and shoved in a fridge that is) are a bunch of sanctimonious goody two-shoes with sticks up their bums. You spend your days getting punched by demons or aliens and what's your reward at the end of it? Nothing but the satisfaction of a job well done.
Heroism, who's got time for it? Now villainy, that's where it's at. Supervillains get all the best names, the best costumes and probably get invited to all the really cool parties where the popular kids hang out. Sure, you'll probably get caught by a hero and chucked in prison, but you'll be out again in a week tops.
We all say we root for the good guys, but deep down it's the villains we really love. The heroes on this list agree, that's why they've, at various points in their career, tossed away their bright spangly outfit for something darker, stuck their tongue out at their teammates and gone to bat for the bad guys instead.