Mickey Mouse was co-created by Walt Disney and Ub Iwerks in 1928. While Walt Disney played a crucial role in defining Mickey's personality and provided the character's original voice, it was actually Ub Iwerks who designed Mickey Mouse and single-handedly animated the first Mickey cartoon. The character was created after Disney lost the rights to his earlier character Oswald the Lucky Rabbit, and Mickey was intended as a replacement. The name "Mickey" was suggested by Disney's wife, Lillian, changing it from the original idea "Mortimer Mouse".
