Nightmare Castle (Italian: Amanti d’oltretomba) is a 1965 Italian horror film directed by Mario Caiano. The film stars Paul Muller, Helga Liné and Barbara Steele in a dual role. The film is set in a castle where Stephen Arrowsmith does experiments involving the regeneration of blood. After finding his wife with the gardener, he kills them both and uses their blood to rejuvenate his loyal assistant Solange.