ONe actor that has captured my attention recently is Robin Williams. He's done some very good work, but usually in comedy roles (Patch Adams, Flubber, etc). But recently, he's been expanding into some very good stretch roles.
In Insomnia, he plays the killer. He was so convincing for me, it was very creepy.
I have not yet seen ONe Hour Photo, as I've heard it's a slow movie. Will be interesting to see how Williams digs deeper into the psychopath.
He's one scary dude sometimes.