Hmm…this probably seems too easy, but the one that's freshest in my mind is pretty recent: Anton Chigurh from No Country for Old Men. A truly unique bad guy; the actor is Javier Bardem.

Robert Mitchum also comes to mind in two straight-up classics: The Night of The Hunter and the original Cape Fear. I don't know either character's name.
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This ain't for the underground. This here is for the sun."
-Saul Williams