12 Angry Men is a 1957 American legal drama film directed by Sidney Lumet in his feature directorial debut, adapted from a 1954 teleplay of the same name by Reginald Rose. A critique of the American jury system during the McCarthy Era, the film tells the story of a jury of twelve men as they deliberate the conviction or acquittal of a teenager charged with murder on the basis of reasonable doubt; disagreement and conflict among the jurors forces them to question their morals and values. It stars an ensemble cast, featuring Henry Fonda (who also produced the film with Rose), Lee J. Cobb, Ed Begley, E. G. Marshall, and Jack Warden.

An independent production distributed by United Artists, 12 Angry Men received acclaim from critics, despite a lukewarm box-office performance. At the 30th Academy Awards, it was nominated for Best Picture, Best Director and Best Screenplay. It is regarded by many as one of the greatest films ever made.

In 2007, it was selected for preservation in the United States National Film Registry by the Library of Congress as being "culturally, historically or aesthetically significant". Additionally, it was selected as the second-best courtroom drama ever (after 1962's To Kill a Mockingbird) by the American Film Institute for their AFI's 10 Top 10 list.