<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 Mary `` Boo '' , a three - 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 also happens to be the daughter of Rob Gibbs who worked as a story artist on the film . </Li> <Li> Steve Buscemi as Randall Boggs , a purple eight - legged lizard monster with a chameleon - like ability to change 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 reminiscent of Selma Diamond 's who administrates for Scarefloor 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 aka . 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 assistant . He is generally incompetent and is often bullied by Randall . </Li> <Li> Dan Gerson as Smitty and Needleman , two goofy adolescent monsters with cracking voices who work as janitors and operate the Door Shredder when required . The pair of them idolize Sulley and are generally seen as a nuisance by Mike . </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
who voices mike and sully in monsters inc
John Goodman as James P. `` Sulley '' Sullivan Billy Crystal as Michael `` Mike '' Wazowski