I was gonna come in here and say The Governor from The Walking Dead, but I see that's already been done. The actor who plays him REALLY does the character justice. He's probably the best manipulative psycho on TV today.
For movies, I'd definitely go for Lee Woo-Jin from Oldboy. The guy is simply insane. Not only is he a billionaire master manipulator, but everything he does to Oh-Dae Su in the movie, no matter how small, is not without reason. Everything falls into the bigger picture.
Mr. Blonde from Reservoir Dogs, I'm surprised he hasn't been mentioned yet, is one of my favorite villains of all time. Completely ruthless and belligerent, with no remorse towards anyone what so ever.
A few others would include Alex DeLarge from A Clockwork Orange, The Joker from The Dark Knight, Max Cady from Cape Feare (I can't decide whether Robert Mitchum's version is better or if Robert De Niro's is... they both had their merits) and lastly, Frank Booth from Blue Velvet.