Where you've seen him before:  "Monsters," "Bones"

Breakout Roles: "Argo," "Killing Them Softly"

Why:  During the introduction that Ben Affleck did for his cast at the "Argo" premiere during the Toronto Film Festival, he called Scoot McNairy "the best actor you don't know yet," and his two films this fall may prove Affleck right.  In "Argo," he's one of the Americans trapped in the Canadian ambassador's home, and he does wrenching work as a man trying to guarantee his wife's safety in an impossible situation.  In "Killing Them Softly," he's one of the thugs whose plan to rob a poker game kicks off a deadly string of events, a complete moral failure of a man whose weakness drags down everyone in his gravitational pull.  He's totally physically different in both, vanishing into the movies, and while you may not know him yet, I have a feeling he's about to turn "Scoot" into a household name.

- Drew McWeeny