Character He Plays: Cousin Sean
Boston Guy's Assessment: Corrigan's accent is definitely more of a New York accent, but it's good enough to get by. 

My favorite actor Kevin Corrigan is basically playing Kevin Corrigan in The Departed, which is as amazing as it sounds, but it's also why he's smack dab in the middle of this list. Corrigan's a Bronx guy, and he sounds like one, but he's charismatic enough—and in the movie so little—that it doesn't really matter one way or the other.