Mortimer is the name that Walt Disney had originally suggested for Mickey Mouse. Mickey Mouse was born in Walt's imagination in March, 1928, when Walt was returning from an unsuccessful business meeting in New York City at which he lost the rights to an earlier cartoon character, Oswald the Lucky Rabbit. Walt and his wife, Lilly, were riding the train back to California when Walt started to doodle a cartoon mouse. He thought the mouse should be named Mortimer. Lilly didn't like that idea and suggested "Mickey." When they got to California, Walt brought his original sketches to Ub Iwerks, who refined and developed the appearance of the character. Mickey Mouse (not Mortimer) debuted in "Steamboat Willie" at the Colony Theatre in New York City on November 18, 1928, and was a great success. You can find lots more information about all of your favorite Disney characters in our online Disney Archives.