The Wizard of Oz is a 1939 American musical fantasy film produced by Metro-Goldwyn-Mayer (MGM). An adaptation of L. Frank Baum's 1900 children's fantasy novel The Wonderful Wizard of Oz, it was primarily directed by Victor Fleming, who left production to take over the troubled Gone with the Wind. It stars Judy Garland, Frank Morgan, Ray Bolger, Bert Lahr, Jack Haley, Billie Burke, and Margaret Hamilton. Noel Langley, Florence Ryerson, and Edgar Allan Woolf received credit for the screenplay, while others made uncredited contributions. The music was composed by Harold Arlen and adapted by Herbert Stothart, with lyrics by Edgar "Yip" Harburg.

The Wizard of Oz is celebrated for its use of Technicolor, fantasy storytelling, musical score, and memorable characters. It was a critical success and was nominated for five Academy Awards, including Best Picture, winning Best Original Song for "Over the Rainbow" and Best Original Score for Stothart; an Academy Juvenile Award was presented to Judy Garland. While the film was sufficiently popular at the box office, it failed to make a profit for MGM until its 1949 re-release, earning only $3 million on a $2.7 million budget, making it MGM's most expensive production at the time.

The 1956 television broadcast premiere of the film on CBS reintroduced the film to the public. According to the U.S. Library of Congress, it is the most seen film in movie history. In 1989, it was selected by the Library of Congress as one of the first 25 films for preservation in the United States National Film Registry for being "culturally, historically, or aesthetically significant"; it is also one of the few films on UNESCO's Memory of the World Register. The film was ranked second in Variety's inaugural 100 Greatest Movies of All Time list published in 2022. It was among the top ten in the 2005 BFI (British Film Institute) list of "50 films to be seen by the age of 14" and is on the BFI's updated list of "50 films to be seen by the age of 15" released in May 2020. The Wizard of Oz has become the source of many quotes referenced in contemporary popular culture. The film frequently ranks on critics' lists of the greatest films of all time and is the most commercially successful adaptation of Baum's work.