Bayaz, First of the Magi, from 'The Blade Itself' by Joe Abercrombie.
He's a borderline god-like mage who has a hand in every plot. His ability to manipulate people, factions, even empires, is masterful, and nothing happens that he isn't already expecting.
Physically he's an unassuming, fairly regular looking older man. He's tall and broad, with a butcher's look about him, but a certain intelligence is evident in his face and his expressions.
His way of dealing with his enemies is what makes him so damn badass. Bayaz will gladly sit down and talk to someone who means him harm. He hates formality, so he'll just talk to a king or emperor like they're a regular person, but if they get above their station and threaten him, shit gets real.
Seriously, you don't want to mess with him. When he's pissed the very space around him starts to warp and darken, and if he wants someone dead, he can basically just turn them inside out with his mind.
Don't fuck with Bayaz.