Banksy

Banksy is the pseudonym of a British graffiti artist, political activist and painter, whose identity is unconfirmed. His satirical street art and subversive epigrams combine irreverent dark humour with graffiti done in a distinctive stencilling technique. Such artistic works of political and social commentary have been featured on streets, walls, and bridges of cities throughout the world. 

He has just caused controversy with an intro he did for The Simpsons. Knowing Banksy's political ideals, I can't help feeling that he has had a joke on The Simpsons creators without them getting it. His intro shows Asian sweatshop workers making Simpsons merchandice and portrays 20th Century Fox as a prison.

Here is a piece he did called Naked Man image on the wall of a sexual health clinic in Park Street, Bristol.