Writer and filmmaker William Peter Blatty, author of the famed 1971 novel The Exorcist that he helped turn into one of the most iconic supernatural horror films of all time, died Thursday at age 89.

William Friedkin, who directed The Exorcist movie based on Blatty’s Oscar-winning screenplay, tweeted this morning:

A screenwriter and author, Blatty eventually wrote and directed The Exorcist III after an original sequel to the franchise he had no involvement with; the threequel was based on his 1983 novel Legion. He also wrote and directed 1980’s The Ninth Configuration starring Stacey Keach, also based on his novel. He wrote 13 books in all.

Fox just finished Season 1 of The Exorcist, a drama series based on Blatty’s work.

Blatty, born in New York to Lebanese parents, wrote several screenplays in the 1960s working especially with Blake Edwards including A Shot In The Dark (1964), What Did You Do in the War, Daddy? (1966), Gunn (1967) and the musical Darling Lili (1970).