O.S.S. is a 1946 American war spy film directed by Irving Pichel and starring Alan Ladd, Geraldine Fitzgerald and Patric Knowles. Produced and distributed by Paramount Pictures, it portrays the activities of the Office of Strategic Services during World War II. The screenplay was written by Richard Maibaum, a World War II veteran who would later write twelve of the first fifteen James Bond films. Maibaum, a former Broadway actor, also narrates the film.

Irving Pichel was an American actor and film director, who won acclaim both as an actor and director in his Hollywood career.