The Exorcist is a movie first released in 1973, based on the 1971 novel by William Peter Blatty, which was based on the case of Robbie Mannheim. The novel and the movie depict a girl possessed by the devil and efforts at exorcism by a priest at the request of the girl's mother. It had several sequels, the first of whom (1977) featured the same actress (Linda Blair) as the possessed girl from the first film.
The movie caused a national sensation in the United States and was successful worldwide despite attempts at censorship in many countries. It broke the record for the biggest grossing movie of all time, and was nominated for ten Academy Awards. But liberals disliked its disturbing depiction of the devil and its favorable characterization of Christianity, so it won only two minor Oscars: Best Adapted Screenplay and Best Sound.
It was re-released in 2000 with the original edited scenes reinstated. It is widely credited as being the most successful film of the horror genre and considered a landmark piece of film-making in general.