|Affiliations|| Circus Freak Trio|
Negative 10 (formerly)
|Occupation(s)|| Circus performer (formerly)|
|Powers and Abilities|
|Voice Actor|| Jeff Doucette (Original Series)|
David Kaye (Omniverse)
|First Appearance||Last Laugh|
Thumbskull is a hulking figure and his size often intimidates others. As his name implies, he has a giant toenail on his otherwise bald forehead.
In Omniverse, he looks more muscular and his chin is much larger. He now has one large finger on his hands and feet, complete with a single fingernail on his chest and the thumb on his forehead is a lighter green.
Thumbskull first appeared in Last Laugh as a henchmen working under Zombozo. He later then appeared in Ghostfreaked Out when the Circus Freak Trio went solo and they were forced to work under Ghostfreak until his defeat. Their last on screen appearance was in Ben 10 vs. The Negative 10 in a league of Ben’s villains working under the Forever King to steal the Sub Energy for him.
He is usually easily beaten by Ben, normally even worse than the others were. His name is a play on the insult "numbskull", as well as the obvious appearance gag.
Thumbskull appears in Something Zombozo This Way Comes when he and his team are re-hired by Zombozo to distract Ben while he is feeding off people's fear. He is defeated by Frankenstrike when he drops a High Striker on him. After Zombozo escaped he and his team are arrested by the Plumbers.
Powers and Abilities
Thumbskull has incredible strength (though inferior to that of Four Arms).
Thumbskull has limited intelligence, normally serving as the "brawn" of the group, as he is easily outsmarted by intelligent opponents.
- Last Laugh (first appearance)
- Ghostfreaked Out
- Ben 10 vs. the Negative 10: Part 1
- Ben 10 vs. the Negative 10: Part 2
Ben 10: Omniverse
- Something Zombozo This Way Comes (first re-appearance)