After recently seeing the movie, Divergent, I'm voting for Theo James as Harry. I was stunned when I saw him onscreen as he is the image of the Harry Dresden that I have in my head. Of course, he needs a few inches of height but 6' 1" isn't too bad. Also, my image of Harry has thinner lips. I love the 'resonant baritone' of Theo's voiced as well.

I'd post a photo but I just can 't figure out how to do that on my smart phone. Hey, I'm old...