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Lots of classics already mentioned so I'll stick to relatively recent movies: -Takers. Very underrated movie btw except for the $hitty ending that didn't really make cinematic sense. -Public Enemy: Dillinger was a freaking badass, like most Johnny Depp roles.
On a more serious note, I thought Megan Fox's clothes were the bad guy in Transformers, until I noticed the peculiar-looking Megatron fellow.
Goodfellas, Scarface, and some Clint Eastwood films like High Plains Drifter comes to mind. Also the original Darth Vader and the Joker (Jack Nicholson or Heath Ledger).