Curse of the Crimson Altar is a 1968 British horror film directed by Vernon Sewell and starring Christopher Lee, Boris Karloff and Mark Eden. The film was produced by Lewis M. Heyward for Tigon British Film Productions. The film was released as The Crimson Cult in the U.S. The story is based on the book The Dreams in Witch House by H. P. Lovecraft. The house in the film is Grim’s Dyke House in Harrow Weald, Middlesex, England, the former home of William S. Gilbert.