Banksy is a graffiti artist from the UK. Google can tell you everything I know about him…. but to give you a general idea, the wikipedia article about him: “Banksy is widely considered to be a talented artist; he uses his original street art form to promote alternative aspects of politics from those promoted by the mainstream media.”
He came to my attention after I saw this article – about a fake cave painting he had planted in the British Museum, of a caveman pushing a shopping trolley. He’s pulled similar tricks in a few other museums, and has a lot of interesting artwork and exploits to his name (I like his parachuting cow).