Definitely Damon Salvatore. He's the guy I started looking at when I first started. Everything from eye contact (a big one), facial expressions, mannerisms, and style. When in doubt, I ask, "what would Damon do?"
My other huge one is Harvey Specter from Suits played by Gabriel Macht. I love that show. Harvey is just super cool, confident, and smooth. He always knows what to say and is super tough to crack. Always dressed to the nines. Definitely one hell of a bad ass.
I try to be a hybrid of these two.