Google: Ub Iwerks.
Ub Iwerks and Mickey mouse.
FRiends don't let FRiends Google!
Ah yes... the fella who worked side-by-side with Disney from 1919 to 1929, and after eleven years on his own came back and continued to work for Disney on animations, special effects, and Disneyland attraction design well into the 1960s? That guy?
Yeah, he’s credited with improving on Disney’s initial slightly pointy-eared “Mortimer Mouse” and for doing a lot of the animations in concert with Les Clark, Wilfred Jackson (both on “Steamboat Willie”), Ralph Wright, George Stallings, Bill Peet, and many others...
Including my personal favorite Vlad Tytla, who animated Chernobog in “Fantasia” (oddly, Tytla worked from photo references for whom the live subject was the above-mentioned Wilfred Jackson).
All of the above under the direction of Walt Disney Studios.