Lot of good ones mentioned.
What about Depp in Blow or Depp in Donnie Brasco (he was a cop in this one so maybe not so much, but he did beat that dude in the bathroom and help cut up bodies.)
And how the hell can someone not like Menace II Society? it's classic.
edit: Just noticed the person that does not like MIIS is a female, that explains. Not as many female gnagster movie fans.