The Exorcist was probably the scariest novel published in 1971, and the movie based on it was undeniably the most frightening film of the 1970s. Through new editions and sequels, the story continues to terrify audiences.

William Peter Blatty (1928–) got the idea for his novel from a case he studied while a student at Georgetown University in Washington, D.C. An exorcism is a religious ceremony held to expel an evil spirit or demon from a person. Although exorcisms are rare today, the Catholic Church authorized one in 1949 for a Maryland boy who appeared to be possessed. Blatty turned this account into the story of Regan MacNeil, an innocent girl possessed by a demon and the two Jesuit priests who try to save her. The novel was a huge commercial success, spending more than a year on the best-seller (see entry under 1940s—Commerce in volume 3) lists...