<Ul> <Li> John Goodman as James P. "Sulley" Sullivan, a large, furry blue monster with horns and purple spots . Even though Sulley excels at scaring children, he is a gentle giant by nature . At the film's beginning, Sulley has been the "Best Scarer" at Monsters, Inc. for several months running . </Li> <Li> Billy Crystal as Michael "Mike" Wazowski, a short, round green monster with a single big eyeball and skinny limbs . Mike is Sulley's station runner and coach on the scare floor, and the two are close friends and roommates . Mike is charming and generally the more organized of the two, but is prone to neurotics and his ego sometimes leads him astray . He is dating Celia Mae, who calls him "Googly - Bear". </Li> <Li> Mary Gibbs as Boo, a two - year - old human girl who is unafraid of any monster except Randall, the scarer assigned to her door . She believes Sulley is a large cat and refers to him as "Kitty". In the film, one of Boo's drawings is covered with the name "Mary". The book based on the film gives Boo's "real" name as Mary Gibbs, the name of her voice actress, who is also the daughter of one of the film's story artists, Rob . </Li> <Li> Steve Buscemi as Randall Boggs, a purple, eight - legged lizard monster with a chameleon - like ability to change his skin color and blend in completely with his surroundings . He is a snide and preening character who makes himself a rival to Sulley and Mike in scream collection . </Li> <Li> James Coburn as Henry J. Waternoose III, an arthropodic monster with a crab - like lower body . Waternoose is the CEO of Monsters, Inc., a job passed down through his family for three generations . He acts as a mentor to Sulley, holding great faith in him as a scarer . </Li> <Li> Jennifer Tilly as Celia Mae, a gorgon - like monster with one eye and tentacle - like legs . Celia is the receptionist for Monsters, Inc. and Mike's girlfriend . </Li> <Li> Bob Peterson as Roz, a slug - like monster with a raspy voice who administrates for Scare Floor F where Sulley, Mike, and Randall work . At the end of the movie, it is revealed that Roz is "Agent Number 1" of the CDA, and has worked undercover at Monsters, Inc. for two and a half years . </Li> <Li> John Ratzenberger as Yeti a.k.a. The Abominable Snowman, a furry white monster who was banished to the Himalayas . He was inspired by the Abominable Snowman from the 1964 Rankin / Bass animated special Rudolph the Red - Nosed Reindeer . </Li> <Li> Frank Oz as Jeff Fungus, Randall's red - skinned, three - eyed, beleaguered assistant . </Li> <Li> Dan Gerson as Smitty and Needleman, two goofy monsters with cracking voices, who work as janitors and operate the Door Shredder when required . </Li> <Li> Steve Susskind as Jerry Slugworth, a red, seven - fingered monster, who manages Scare Floor F and is a good friend of Waternoose . </Li> <Li> Bonnie Hunt as Ms. Flint, a female monster, who trains new monsters to scare children . </Li> <Li> Jeff Pidgeon as Thaddeus "Phlegm" Bile, a trainee scarer for Monsters, Inc . </Li> <Li> Samuel Lord Black as George Sanderson, a chubby, oranged - furred monster with a sole horn on top of his head . A running gag throughout the film involves George repeatedly making contact with human artifacts (such as socks and the like which cling to his fur via static), prompting his scare coach to trigger "23--19" incidents with the CDA resulting in him mobbed, shaved bald, and sterilized . He is good friends with Pete "Claws" Ward . </Li> <Li> Phil Proctor as Charlie, George's assistant with sea - green skin and tendrils for limbs . He is friends with George, Mike, and Sulley, but is quick to call the CDA on his scarer at the drop of a hat . </Li> <Li> Joe Ranft as Pete "Claws" Ward, a blue monster with razor - sharp claws and horrifying breath . </Li> </Ul> <Li> John Goodman as James P. "Sulley" Sullivan, a large, furry blue monster with horns and purple spots . Even though Sulley excels at scaring children, he is a gentle giant by nature . At the film's beginning, Sulley has been the "Best Scarer" at Monsters, Inc. for several months running . </Li> <Li> Billy Crystal as Michael "Mike" Wazowski, a short, round green monster with a single big eyeball and skinny limbs . Mike is Sulley's station runner and coach on the scare floor, and the two are close friends and roommates . Mike is charming and generally the more organized of the two, but is prone to neurotics and his ego sometimes leads him astray . He is dating Celia Mae, who calls him "Googly - Bear". </Li> <Li> Mary Gibbs as Boo, a two - year - old human girl who is unafraid of any monster except Randall, the scarer assigned to her door . She believes Sulley is a large cat and refers to him as "Kitty". In the film, one of Boo's drawings is covered with the name "Mary". The book based on the film gives Boo's "real" name as Mary Gibbs, the name of her voice actress, who is also the daughter of one of the film's story artists, Rob . </Li>

Who does mike's voice in monsters inc