The Knucklehead is a character from the episode, "The Party Animal". He appears when noticing that Sylvia doesn't have the correct outfit to go on stage. Upon learning about the dress code, Sylvia gets mad at the knucklehead and says that all the knuckleheads want to do is make every girl look stupid. After Sylvia makes herself look like a clown, the knucklehead allows her to pass through.
"The Party Animal" (First appearance)(Last appearance)
He can be considered the opposite of Moose, as Moose is the strongest of the Watchdogs and the Knucklehead is the strongest of the Fist Fighters.