Search found 1 match: Kathy Bates

There's a few I can think of:
Robin Williams in One Hour Photo, Insomnia, and maybe even Death to Smoochy (all kind of dark roles that are odd for the usually comedic Williams)
Jim Carrey in Eternal Sunshine of the Spotless Mind (More serious than most of Carrey's films)
Adam Sandler in Punch Drunk Love (More serious than comedic)
William Hurt in A History of Violence (As far as I know, it is one of his first gangster type characters)
Elijah Wood in Sin City (the former child actor who seemed to play mostly happy roles turns into[spoiler]a murderer who eats his victims[/spoiler] Really?)
Kathy Bates in Misery (seems like a really sweet older lady most of the time, except when she goes psycho on James Caan)
Christian Bale in American Psycho (only way I can really explain this one is that it seems like a role he wouldn't play)
Kevin Costner in Mr. Brooks (Seems to be in mostly light hearted films, but not in this where he plays a [spoiler]a model citizen whose favorite hobby is killing[/spoiler])
Steve Zahn in Riding in Cars with Boys and A Perfect Getaway (more serious roles for the usually comedic Zahn)

I'm sure there are more, but I'll leave it here.