US author and filmmaker William Peter Blatty, best known for writing The Exorcist, has died at the age of 89 on Thursday at a hospital in Bethesda, Maryland. The Exorcist was published as a novel in 1971, with the hugely successful big screen adaptation, also written by Blatty, following two years later. <br/><br/>Despite a troubled production and a muted launch, the film went on to become one of the highest grossing in history and is considered by critics to be a classic horror movie.The cause of death was multiple myeloma, a form of blood cancer.

US author and filmmaker William Peter Blatty, best known for writing The Exorcist, has died at the age of 89 on Thursday at a hospital in Bethesda, Maryland. The Exorcist was published as a novel in 1971, with the hugely successful big screen adaptation, also written by Blatty, following two years later. <br/><br/>Despite a troubled production and a muted launch, the film went on to become one of the highest grossing in history and is considered by critics to be a classic horror movie.The cause of death was multiple myeloma, a form of blood cancer.