Steamboat Willie is a 1928 American animated short film directed by Walt Disney and Ub Iwerks. It was produced in black-and-white by the Walt Disney Studio 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 unreleased The Gallopin' Gaucho. Steamboat Willie is the third of Mickey's films to have been produced, but it is the first to have been distributed, because Disney had seen The Jazz Singer (1927) and became determined to produce one of the first fully synchronized sound cartoons.

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

The soundtrack 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 film's title may be a parody of the Buster Keaton film Steamboat Bill, Jr. (1928), which is a reference to the song by Collins. Disney performed all of the voices in the film's little intelligible dialogue.

Steamboat Willie became the most popular cartoon of its time. It has received wide critical acclaim, for introducing one of the world's most popular cartoon characters and for its technical innovation. It is often considered one of the most influential cartoons ever made. Animators voted it 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, alongside other works published in 1928.

Mickey Mouse was created as a replacement for Oswald the Lucky Rabbit, an earlier character originated by the Disney studio but owned at the time by Universal Pictures. The first two Mickey Mouse films produced, silent versions of Plane Crazy and The Gallopin' Gaucho, had failed to gain a distributor. According to Roy O. Disney, Walt Disney was inspired to create a sound cartoon to greatly increase its appeal, after watching The Jazz Singer (1927). The character of Pete predates Steamboat Willie by multiple years, having appeared as the villain to both Oswald and Disney's first ever cartoon hero, Julius the Cat (an unlicensed derivative character of Felix the Cat) starting with Alice Solves the Puzzle (1925), though he was originally depicted as a bear.

Steamboat Willie became widely recognized as the first cartoon with synchronized sound, but it is not. From May 1924 to September 1926, Dave and Max Fleischer's Inkwell Studios produced 19 sound cartoons, part of the Song Car-Tunes series, using the Phonofilm sound-on-film process. However, the Song Car-Tunes failed to keep the sound fully synchronized, whereas Steamboat Willie was produced using a click track to keep his musicians on the beat. Only one month before Steamboat Willie was released, Paul Terry released Dinner Time, which has a soundtrack but was not a financial success.

In June 1927, producer Pat Powers made an unsuccessful takeover bid for Lee de Forest's Phonofilm Corporation. In the aftermath, Powers hired a former DeForest technician, William Garrity, to produce a cloned version of the Phonofilm system, which Powers dubbed "Powers Cinephone". By then, de Forest was in too weak a financial position to mount a legal challenge against Powers for patent infringement. Powers convinced Disney to use Cinephone for Steamboat Willie. Their business relationship lasted until 1930 when Powers and Disney had a falling-out over money, and Powers hired away Disney's lead animator, Ub Iwerks.^{[citation needed]}

Mickey Mouse is piloting a side-wheeler paddle steamer, cheerfully whistling "Steamboat Bill" and sounding the boat's three whistles. Soon, captain Pete appears and orders Mickey off of the bridge. Annoyed, Mickey blows a raspberry at Pete who attempts to kick him, but Mickey rushes away in time and Pete accidentally kicks himself in the rear. Mickey falls down the stairs, slips on a bar of soap on the boat's deck, and lands in a bucket of water. A parrot laughs at him, and Mickey throws the bucket on its head in retaliation.