12. Christoph Waltz - Doctor Faustus
Having already committed one great villain to screen in Inglourious Basterds' Hans Landa, one very good one in Water For Elephants' volatile August, and two terrible ones for The Three Musketeers and The Green Hornet (mostly because of the films, rather than his performance), Waltz has previous as grotesque villain figures, and with some notable success. Though his background is in TV, he has brought a theatricality to his big screen performances that works particularly well for grand, scheming villains, particularly when they have a flamboyant edge to them, and he has both the intellect and the accent to pull off the Austrian criminal mastermind, Faustus. Like Landa, Faustus would require an imposing, but not quite physically threatening performance - he is menacing without hulking stature, and his power is very much of the mind and of language, and that would suit Waltz beautifully. Alternatively, Michael Fassbender would be an incredible Faustus, given his ability to exude dark charisma and high-intellect, but since those characteristics are basically what landed him the role of Magneto, it's less likely that he would be cast, especially with Marvel likely to at least attempt some sort of X-Men cross-over at some point in the future for the MCU.
Who It Definitely Shouldn't Be: Zach Galifianakis, because sometimes a beard is just not enough.