William Friedkin, 1973. 12-year-old Regan possessed; two priests called. Highest-grossing R-rated film for years.
From Wikipedia
The Exorcist is a 1973 American supernatural horror film directed by William Friedkin from a screenplay by William Peter Blatty, based on his 1971 novel. The film stars Ellen Burstyn, Max von Sydow, Jason Miller, and Linda Blair, and follows the demonic possession of a young girl and the attempt to rescue her through an exorcism by two Catholic priests.