Professor Exclamation, also referred to as Jack Ampersand, is a recurring villain in Hamster & Gretel. He appears to be an inventor, who decided to become a supervillain after losing his elbows in an industrial accident (which may explain his short arms), deciding that if he couldn't bend his arms, he would bend everyone else to his will. Professor Exclamation is the very first villain that Hamster, Gretel, and Kevin have faced in the series, debuting in the episode "Empower Failure", the series' first episode. He also has a son named Nordle, a prodigy with altered DNA, whom he wishes to grow up becoming an evil genius like himself.