Gaslight is a 1944 American psychological thriller film directed by George Cukor, and starring Charles Boyer, Ingrid Bergman, Joseph Cotten and Angela Lansbury in her film debut. Adapted by John Van Druten, Walter Reisch, and John L. Balderston from Patrick Hamilton's play Gas Light (1938), it follows a young woman whose husband slowly manipulates her into believing that she is descending into insanity.

A remake of the 1940 British film of the same name directed by Thorold Dickinson, Cukor's version had a larger scale and budget than the earlier film, and lends a different feel to the material. To avoid confusion with the first film, Cukor's version was originally titled The Murder in Thornton Square in the UK. The film features numerous deviations from the original stage play, though the central drama remains that of a husband trying to drive his wife insane in order to distract her from his criminal activities.

Gaslight was released theatrically on May 4, 1944, by Metro-Goldwyn-Mayer to critical acclaim, and received seven nominations for the 17th Academy Awards, including for Best Picture, winning two: Best Actress (for Bergman); Best Production Design. In 2019, the film was selected for preservation in the United States National Film Registry by the Library of Congress as being "culturally, historically, or aesthetically significant".