The Murderer X (Spanish: El asesino X) is a 1955 Mexican crime thriller film directed by Juan Bustillo Oro and starring Carlos López Moctezuma, Manolo Fábregas and Prudencia Grifell. It was shot at the Clasa Studios in Mexico City. The film's sets were designed by the art director Javier Torres Torija. Stylistically a film noir, it is set in the United States with a plot revolving around amnesia.