I'm surprised no one mentioned the HEATH LEDGER and his performance as the Joker.
Only he could put so much character he put into such a bastard nihilist, its amazing! Even in death he steals every scene in The Dark Knight.
Christopher Walken, he tends to put a lot of class/humor in his roles in one way or another. Theres never a dull moment with him on screen, Suicide Kings is where he really stood out to me.
And VA Troy Baker (everything he does is great from Booker Dewitt to Joel) but specifically for his role as Kanji Tatsumi from Persona 4. He really has that believability as a man just trying to get through high school and be accepted, the moments when Troy Baker acts out the Kanji Social Links are down right astounding. And then there's his shadow... pffft it may be silly but damn he nailed it, even the director of the game prefered him over the japanese VA.