The "Monsters. Inc." characters managed to bring an entirely new look to the old stories about monsters under the bed. The best part about the pixar movie is the 'Monsters, Inc." characters managed to show millions of children there truly wasn't anything to be scared about because the monsters living under the bed were just as scared of you as you were of them.
James P. "Sulley" Sullivan
Sulley is the lynch pin of the "Monsters, Inc." characters as the conscience of the entire community. It is he who decides that Boo is someone who needs to be cared for instead of turned over to the monster authorities. Sulley shows Boo that monsters can be lovable and neurotic at the same time.
Boo is the little girl who follows Sulley and Mike from her own world into theirs. Boo is one of the "Monsters, Inc." characters who manages to show the the monsters that humans are not something to be feared. Her exploits are what truly make the movie great.
Billy Crystal voices Mike and much like John Goodman does with Sulley, he gives his "Monsters, Inc." character equal parts professional child scarer and neurotic, fearful employee. Mike and Sulley are partners and best friends, and eventually become a kind of parental team to Boo.
Henry J. Waternoose
The leader of all the "Monsters. Inc." corporation, Mr. Waternoose is the founder and the owner of the monster plant where Mike and Sulley work. Waternoose originally seems to be a benevolent boss, but he is eventually shown to be far more malevolent than anyone knew.