William Peter Blatty (January 7, 1928 – January 12, 2017) was an American writer and filmmaker best known for his 1971 novel The Exorcist and for the Academy Award-winning screenplay of its film adaptation. He also wrote and directed the sequel The Exorcist III. Some of his other notable works are the novels Elsewhere (2009), Dimiter (2010) and Crazy (2010). WIKIPEDIA
