James P. Sullivan (often called "Sulley") is a large, furry blue monster with purple spots, he is a cocky, naturally gifted college student in the Scare Program. He relies on his famous family name rather than hard work, which causes him to clash with his rival and eventual best friend, Mike Wazowski.

Mike Wazowski is a short, round, lime-green monster with a single large eye. he is an ambitious and highly confident student determined to become a top "Scarer".

a mysterious, furry purple monster in the shape of an arch who joins the Oozma Kappa fraternity. he is a New Age philosophy major known for his weird personality, mysterious past (including previous stints in jail), and strange but agile stunts.

is a mature, polka-dotted, octopus-like monster who returns to college to learn scaring after being laid off from his sales job. He is the president of the Oozma Kappa fraternity and acts as the hardworking, grounded "dad" figure of the group.

a college student named Scott Squibbles. He is a soft, five-eyed, jelly-like monster who is a member of the Oozma Kappa fraternity. He is known for living with his doting mom and being very sweet but naïve. Squishy has a very quiet and stealthy personality. This means he is very good at hiding without anyone noticing him. He uses this sneaky skill to help his fraternity win points in the Scare Games.

are conjoined twin monster brothers. They have four arms and share one yellow body. Terri (with an "i") is a joyful dance major with one horn. Terry (with a "y") is a moody math fan with two horns. They belong to the Oozma Kappa fraternity.

Randall ditches Mike to join the elite "Roar Omega Roar" fraternity so he can be cool. During the final round of the Scare Games, a prank goes wrong. Sulley embarrasses Randall, causing him to be laughed at by the entire campus. This humiliation destroys Randall's confidence. It sparks a deep hatred for Sulley and drives him to become the sarcastic, sneaky villain seen in Monsters, Inc..