Billy

Billy is a Maxatomar who made his first appearance in Ken 10.

Appearance
In the original series, 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, he looks just as he did in the original series.

Ben 10,000 (Alternate Timeline)

 * In Ken 10, he makes his first debut as one of Kenny's friends.

Omniverse

 * In Special Delivery, he makes a cameo as one of the villains working for Psyphon.
 * In Bengeance is Mine, he can be briefly seen looking at one of Vilgax's holograms.

Ben 10

 * Ken 10 (first appearance)

Ben 10: Omniverse

 * Special Delivery (first re-appearance; cameo)
 * Bengeance is Mine (cameo)

Trivia

 * He is a parody of Billy from 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."