Caligula is a biographical film focusing on the rise and fall of the Roman Emperor Caligula. It stars Malcolm McDowell, Teresa Ann Savoy, Helen Mirren, Peter O'Toole and John Gielgud. It is the only feature film produced by the men's magazine Penthouse. Producer Bob Guccione, the magazine's founder, intended to produce an explicit adult film within a feature film narrative, which had high production values. He intended to cast Penthouse Pets as extras in unsimulated sexual scenes filmed during post-production by Guccione and Giancarlo Lui.