Les Diaboliques is a 1955 French, black and white thriller, and its title is roughly translated as The Devils or The Fiends, as directed by filmmaker Henri-Georges Clouzot. The film holds a 98% approval rating based on 23 reviews on the Rotten Tomatoes website, and Time Magazine placed it on its top 24 horror films of all time list. In addition, Les Diaboliques holds a spot on Bravo Television’s top 100 films list. By comparison, Alfred Hitchcock’s 1960 film Psycho developed and cemented many staples of the contemporary horror and slasher film genre, which are still in use by filmmakers today. Psycho was preserved by the Library of Congress at the National Film Registry. And like Les Diaboliques, Psycho also holds a place on the Bravo Television Network’s list of the top 100 scariest movie moments; while Entertainment Weekly and Premiere magazines both listed Psycho on their lists of the top 100 movies of all time. Psycho also holds a number of spots on a variety of The American Film Institute’s best of lists, including the coveted spot as the number one thriller of all time on its 100 Years, 100 Thrillers list; as well as the eighteenth position on the 100 Years, 100 Movies list. Finally, actor Anthony Perkins’s character, Norman Bates, holds the number two position on The American Film Institute’s 100 Years, 100 Villians list (beat out by Anthony Hopkin’s character of Hannibal Lecter from 1991’s The Silence of the Lambs). This essay will examine the ties between these two classic films, including an overview of what formal elements they have in common; as well as an examination of what areas Clouzot’s Les Diaboliques may have influenced Hitchcock’s Psycho.