The Exorcist III is a 1990 American supernatural psychological horror film written for the screen and directed by William Peter Blatty, based on his 1983 novel Legion. It is the third installment in The Exorcist film series, and the final installment in Blatty's "Trilogy of Faith" after The Ninth Configuration (1980). The film stars George C. Scott, Ed Flanders, Jason Miller, Scott Wilson, Nicol Williamson, and Brad Dourif.