In case you don't know who he is: he was John Thornton in BBC's North & South, where he became an overnight sensation as fans crashed the BBC forums trying to find out who he was.
Then he was in BBC's Robin Hood as the villain's henchman Sir Guy of Gisborne. The show was pretty badly written, but there was some very interesting chemistry between him and Maid Marion, as well as between him and the cartoonishly evil Sheriff of Nottingham.
After that, he was Lucas North in Spooks (MI-5, in the US), which I can't say anything about without spoiling the story. He also had a small role as a Nazi spy and assassin in Captain America, which I have not seen.
Then, he was Thorin Oakenshield in The Hobbit, king of the Dwarves.
Usually actors do best in roles that are close to their own personality, or at least when they start out anyway. So, it surprised me how good-natured, self-effacing and shy he seems in real life. At the same time, he seems perfectly comfortable with playing dark, angry people, with a lot of barely-reigned-in intensity, and sometimes with a slightly tormented air. I find his interviews extremely relatable, and I don't know why but there are certain glimpses that remind me so much of my INFP as well (so I could be projecting).
Anyway, here's a decently recent interview:
Older interview with *major spoilers* for Spooks:
I suck at typing people, so I'm not even going to try. Anyone?