A robot who attends Elmore Junior High. Being a robot, he is incredibly intelligent and ranks first in the entire school. His body is as hard as scrap metal.

A male light-blue cat who is both Darwin's brother and best friend. He attends Elmore Junior High, where he often causes chaos or plays pranks. He is Penny's boyfriend and his full name is Gumball Watterson. He is two years older than Darwin.

A female Tyrannosaurus Rex who is massive in size. She is capable of speech and is one of the characters Gumball fears most, mainly because he doesn't want to be stepped on. Her full name is Tina Rex.

A ghost girl with a dark personality. She wears a skull hairpin and has hair covering one of her eyes. She has a crush on Darwin. Although she is 327 years old, she attends Elmore Junior High. Since her father is a ghost, she has been a ghost since birth. Her abilities include teleportation, possession, and spirit manipulation. As a ghost, she cannot eat food, but she can pass through walls and doors. If her name is called five times, she is forcibly summoned, a trait shared by other ghosts. She is a fan of Emo music. Her full name is Carrie Krueger.

A cactus who is in a relationship with Alan. She loves vegetables, is female, and attends Elmore Junior High. Her body is covered in thorns. Her full name is Carmen Verde.

A female who is Gumball's girlfriend and can shapeshift into various animals. She is a cheerleader and possesses antlers and wings, though she cannot fly with them. She attends Elmore Junior High and is the only one who openly dislikes Tobias. Her full name is Penny Fitzgerald.

His full name is Tobias Wilson. He is a multicolored cloud-like entity who wears a green headband. He isn't very popular but is very wealthy; he once became Darwin's friend by paying him. He attends Elmore Junior High.

His full name is Alan Keane. He is a male balloon who is dating Carmen. He pops easily and floats well. He attends Elmore Junior High.

A female cloud who comes from a wealthy family and attends Elmore Junior High. There was an episode where she confronted Carmen to try and date Alan. She has extreme emotional swings; when angry or sad, she can trigger storms or rain. Her full name is Masami Yoshida.

A banana who enjoys performing comedy or teasing others. He tells dad jokes and puns, though most people find them unfunny. He has a habit of peeling his own skin.