#4: Monsters, Inc (2001)
Toy Story is one of the most popular animation films of all times, with an ensemble cast that we all know and love. But did you know that the original choice for Buzz Lightyear in Toy Story was Billy Crystal? He turned the role down, however, and it became the voice of Tim Allen.
Crystal went on to say it was one of the biggest mistakes of his career, and when the opportunity to voice Mike Wazowsky in Monsters, Inc. came up, he wasn’t about to miss this opportunity. While Monsters, Inc. never reached quite the same success that Toy Story had, it was still a box office success and remains a beloved animation.