Walt Disney and Ub Iwerks created the cartoon character Mickey Mouse, who made his first appearance in the animated short film "Steamboat Willie" on November 18, 1928. The character was developed as a replacement for Oswald the Lucky Rabbit, whom Disney lost the rights to. Mickey quickly became a cultural icon and the mascot for Disney, representing family entertainment and innocence. His design and personality resonated with audiences, leading to the creation of numerous films, merchandise, and theme park attractions, establishing him as one of the most recognizable characters in animation history.