Initially, Mickey Mouse was characterized by his simple, rounded figure and large eyes. Iwerks brought considerable refinement to Mickey's design, introducing subtle changes that enhanced his personality and expressiveness. He accentuated Mickey's ears and added black circles to his eyes, giving the character a more distinctive and endearing appearance.
Iwerks also played a pivotal role in developing the early Mickey Mouse animations. He pioneered innovative techniques such as "straight ahead" and "pose-to-pose" animation, which allowed for greater fluidity of movement and a more dynamic portrayal of the character. His groundbreaking contributions helped establish Mickey Mouse as a beloved icon and a worldwide cultural phenomenon.