William Peter Blatty (January 7, 1928 – January 12, 2017) was an acclaimed American writer, director, and producer, renowned for his groundbreaking work in horror fiction. Blatty's most famous creation, The Exorcist, a novel published in 1971, has left an indelible mark on the genre. His adaptation of this novel into a screenplay for the film of the same name in 1973 earned him an Academy Award for Best Adapted Screenplay, alongside nominations for Best Picture as its producer. The film also secured Blatty a Golden Globe Award for Best Motion Picture – Drama.

Blatty's journey into the world of literature and film began in New York City, where he was born and raised. He furthered his education at Georgetown University, receiving a bachelor's degree in English in 1950, followed by a master's degree in English literature from the George Washington University in 1954. His career took an early turn towards psychological warfare as he joined the United States Air Force, eventually serving in its Psychological Warfare Division and reaching the rank of first lieutenant. Post service, he found a role at the United States Information Agency in Beirut.

Following the monumental success of The Exorcist, Blatty revisited his 1966 novel Twinkle, Twinkle, "Killer" Kane! transforming it into The Ninth Configuration, which was published in 1978 and later adapted into a film that marked Blatty's directorial debut. This work won the Best Screenplay award at the 38th Golden Globe Awards and was also nominated for Best Picture. Despite his disassociation from the first sequel of The Exorcist, he returned to write and direct the second sequel, The Exorcist III (1990), which he adapted from his 1983 novel Legion. This would be his final directorial and screenplay credit.

Blatty's creative output remained prolific throughout his life. His later notable novels include Elsewhere (2009), Dimiter (2010), and Crazy (2010), further cementing his legacy in the realm of horror fiction and beyond.