This is James Spader. He's been around since the 80's, and he's now on the American version of The Office. His biggest role to date was on Boston Legal.

The reason I thought of him for Smaug is that he's cultivated a screen persona that's rather cold and calculating, and he has this heavy-lidded, reptilian gaze that can be quite chilling. Plus, his voice is wonderfully lazy and disdainful, as if he just barely deigns to bestow his attention on whatever lower form of life he's talking to. I've never heard him try to do an accent other than his own, but what he could do with what he's got would be awesome, in my opinion, anyway.