In William Friedkin's iconic horror film The Exorcist (1973), an adolescent girl, Regan MacNeil, is possessed by evil demon that makes her act in increasingly erratic and immoral ways. She starts to swear urinates on the floor at a house party. Later, she violates herself with cross, violently attacks mother, goes murder two people: friend of Catholic priest come save soul. But it not just Rega...