The Lost Weekend is a 1945 American drama film noir directed by Billy Wilder, and starring Ray Milland and Jane Wyman. It was based on Charles R. Jackson's 1944 novel about an alcoholic writer. The film was nominated for seven Academy Awards and won four: Best Picture, Best Director, Best Actor, and Best Adapted Screenplay. It also shared the Grand Prix at the first Cannes Film Festival, making it one of only four films—the other three being Marty (1955), Parasite (2019) and Anora (2024)—to win both the Academy Award for Best Picture and the highest award at Cannes.

On review aggregator Rotten Tomatoes, the film has an approval rating of 97% based on 70 reviews, with an average rating of 8.4/10. The site's critical consensus reads, "Director Billy Wilder's unflinchingly honest look at the effects of alcoholism may have had some of its impact blunted by time, but it remains a powerful and remarkably prescient film." In 2011, it was selected for preservation in the United States National Film Registry by the Library of Congress as being "culturally, historically, or aesthetically significant."