|This article is about the Maxatomar. You might have been looking for Billy Billions.|
He is somewhat hippo-like in appearance. He has a big pink nose and red hat. He has orange and white skin and wears a blue and white T-shirt.
In Omniverse, Billy looks similar, but his ears and nose are darker and he is noticeably slimmer.
He made his first appearance in Ken 10, where he was one of the few children invited to Ken's tenth birthday party. Impressed with, as well as somewhat jealous of, Kenny's father, Billy revealed that his father is a dentist.
- Ken 10 (first appearance)
Ben 10: Omniverse
- Special Delivery (first re-appearance; cameo)
- Bengeance Is Mine (cameo)
- Cough It Up (cameo)
- No Honor Among Bros (cameo)
- Clyde Five (cameo)
- He is a parody of Billy from the TV series, The Grim Adventures of Billy and Mandy. He is even voiced by the same voice actor, Richard Steven Horvitz.
- According to himself, his dad is "just a boring old dentist."