Sunset Boulevard (1950)
Director: Billy Wilder
Stars: William Holden, Gloria Swanson, Erich von Stroheim, Nancy Olson
This noir is so deliciously intriguing that it can leave any dumbass who doesn't like "boring" black-and-white movies with a craving for more. Often cited as one of the greatest films in American cinema, the film follows a struggling screenwriter who forms an inescapable bond with a delusional (with a capital D) former silent film star, Norma Desmond (played by actual former silent film star, Gloria Swanson).
All of its Academy Award nominations aside, including Best Picture, Sunset Boulevard's most awe-inspiring contribution to movie history has to be its iconic (and maniacal) final lines. Not to spoil the film, but it will leave you questioning the idea of sanity.