Twins of Evil is a 1971 horror film by Hammer Film Productions starring Peter Cushing, with Damien Thomas and the real-life twins and former Playboy Playmates Mary and Madeleine Collinson. It is the third film of The Karnstein Trilogy, based on the vampire tale Carmilla by Sheridan Le Fanu. The film has the least resemblance to the novel and adds a witchfinding theme to the vampire story. Much of the interest of the film revolves around the contrasting evil and good natures of two beautiful sisters, Frieda and Maria Gellhorn. Unlike the previous two entries in the series, this film contains only a brief vampire lesbian element. Some considered the film a prequel to The Vampire Lovers and Lust for a Vampire.