Strangers on a Train is a 1951 American psychological thriller film noir produced and directed by Alfred Hitchcock, and based on the 1950 novel Strangers on a Train by Patricia Highsmith. It was shot in late 1950, and released by Warner Bros. on June 30, 1951, starring Farley Granger, Ruth Roman, and Robert Walker.

The story concerns two strangers who meet on a train, one of whom is a psychopath who suggests that they "exchange" murders so that neither will be caught. The film initially received mixed reviews but has since been regarded much more favorably. In 2021, 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".