Ub Iwerks is well known for being the co-creator of the famous character Mickey Mouse, as he and Walt Disney co-created Mickey Mouse.
Ub Iwerks
 The first few Mickey Mouse and Silly Symphonies cartoons were animated almost entirely by Iwerks. However, as Iwerks began to draw more and more cartoons on a daily basis, he soon found himself unable to cope under Disney's harsh command. After a little while, Iwerks left the Disney company, and created his own animation studio, called The Iwerks Studio, but soon left and went back to Walt Disney Studios.