Banksy.

I do not know a great deal about visual art. I just know what I like when I see it. I've been following this guy's work for a while, although he is not terribly popular or well-known in the U.S. This video about his exhibit at a museum in England is a great introduction to his work, or, if you already know his graffiti (which is usually illegal, so you don't see his face in this video), a look into what he's doing now. Really worth a look!