is a character in the novel The Exorcist, its film adaptations, and the television series The Exorcist. In the 2014 adaptation of the BBC Radio 4 novel, Regan was portrayed by Lydia Wilson. Regan is the daughter of a famous actress Chris MacNeil. Regan is a shy, creative young woman who becomes possessed by the demon Pazuzu. Regan assumes a strange, aggressive behavior that worries and scares her mother, and begins to develop progressively inhuman traits and mannerisms.