Damien Karras

Father Damien "Demis" Karras, SJ, is a fictional character from the 1971 novel The Exorcist, its 1983 sequel Legion, one of the main protagonists in the 1973 film The Exorcist, and a supporting character in The Exorcist III, the 1990 film adaptation of Legion. He is portrayed by Jason Miller.

The Exorcist
In William Peter Blatty's 1971 novel, Father Damien Karras was one of the priests who exorcises the demon from young Regan MacNeil. He is a Jesuit psychiatrist suffering a crisis of faith. He searches for proof to lead an exorcism, yet during his investigation he comes to realize that there is no better way for God to prove His own existence than to reveal the foul presence of a demon; in God's perspective, He appeared not to waste His time on a skeptic, but instead to aid the callings of Father Lankester Merrin to rescue the child victim. During the exorcism, the demon frequently brings up the subject of Karras's mother's death and how he wasn't there to see her die, which seems to trouble Karras emotionally. Karras dies by throwing himself down a flight of stairs in order to purge the demon from his own body after having coaxed it out of Regan's.

Legion
In the 1983 sequel, it is revealed that after the demon departed, another evil spirit invaded Karras's body. Karras was found wandering and amnesiac, and was placed in the care of a mental hospital near Washington, D.C. While incarcerated there, the spirit suppresses Karras's personality and makes forays into the bodies of other patients in order to commit a series of ritual murders.

Adaptations
In the films The Exorcist and The Exorcist III, he is played by Jason Miller (who was in fact educated at the Jesuit University of Scranton).

Jack Nicholson was up for the part of Karras before Stacy Keach was hired by Blatty. According to The Exorcist director William Friedkin, Paul Newman also wanted to portray Karras. Friedkin then spotted Miller following a performance of Miller's play That Championship Season in New York. Even though Miller had never acted in movies, Keach's contract was bought out by Warner Bros. and Miller was signed.

Karras is voiced by Robert Glenister in the 2014 BBC Radio dramatization.

In popular culture
In Percival Everett's Dr. No, an atheistic priest named Damien Karras appears in four chapters in two parts. He assists Wala Kitu and Eigen Vector with nothing before double-crossing them and getting shot to death by the villain, John Milton Bradley Sill.