Steamboat Willie is a 1928 American animated short film directed by Walt Disney and Ub Iwerks. It was produced in black and white by Walt Disney Animation Studios and was released by Pat Powers, under the name of Celebrity Productions. The cartoon is considered the public debut of Mickey Mouse and Minnie Mouse, although both appeared months earlier in a test screening of Plane Crazy and the then yet unreleased The Gallopin' Gaucho. Steamboat Willie was the third of Mickey's films to be produced, but it was the first to be distributed, because Disney, having seen The Jazz Singer, had committed himself to produce one of the first fully synchronized sound cartoons.

Steamboat Willie is especially notable for being one of the first cartoons with synchronized sound, as well as one of the first cartoons to feature a fully post-produced soundtrack, which distinguished it from earlier sound cartoons, such as Inkwell Studios' Song Car-Tunes (1924–1926), My Old Kentucky Home (1926) and Van Beuren Studios' Dinner Time (1928). Disney believed that synchronized sound was the future of film. Steamboat Willie became the most popular cartoon of its day.

Music for Steamboat Willie was arranged by Wilfred Jackson and Bert Lewis, and it included the songs "Steamboat Bill", a composition popularized by baritone Arthur Collins during the 1910s, and the popular 19th-century folk song "Turkey in the Straw". The title of the film may be a parody of the Buster Keaton film Steamboat Bill, Jr. (1928), itself a reference to the song by Collins. Disney performed all of the voices in the film, although there is little intelligible dialogue.

The film has received wide critical acclaim, not only for introducing one of the world's most popular cartoon characters but also for its technical innovation. The short is often considered to be one of the most influential cartoons ever made. Animators voted Steamboat Willie as the 13th-greatest cartoon of all time in the 1994 book The 50 Greatest Cartoons, and in 1998, the film was selected by the United States Library of Congress for preservation in the National Film Registry. The cartoon entered the public domain in the United States on January 1, 2024, as the work was published in 1928.