Onion is an supporting character of Stella and Sam.
Onion appears to have white hair on his body, green and red eyes, a red mouth, a colorful shirt, and pink shoes.
- When he was Stella's age, he played the bongos as revealed in "The Triangle".
- His enemy is Owen.
- As of "The End," he walks down the hallway during Stella and Toby's "wedding".
- At age 8, he saved an origami family from drowning and disarmed a doomsday device.
- Gumball is his favorite student.
- At age 18, he can beatbox.
- Frosty Star Elementary is his job at Frosty Star.