Voice: Low, Friendly. Give John Goodman a listen 

https://www.youtube.com/watch?v=kM8BTiHhk_E 

https://www.youtube.com/watch?v=ifwM5XH9ghk

Sulley is a top scarer under his boss Henry J. Waternoose, III, who is the CEO of Monsters, Inc. Sulley's best friend and sidekick is Mike Wazowski. He is shown to be good-natured, hardworking, and confident, who loves his job as a Scarer and while he basked in the limelight of being Top Scarer and was indeed going for the All-Time Scare Record, he had a humble side in that he was more interested in being a good employee for the company.

Sulley's world, however, is turned upside-down when he discovers a human child, initially and frantically doing everything he can to get rid of her while trying not to get "infected" due to the Monsters' mistaken beliefs that human children are "toxic, deadly, that a single touch could kill them". When left with no choice, he involves Mike, who is more concerned with their career and their well-beings, but as Sulley spends time with the girl, he warms up to her and comes to disregard everything he's ever believed about human children, eventually giving her the name "Boo", and becomes attached to her, like a father.