Mr. Krupp

His favorite student is the nerd Melvin
Absolutely HATES George and Harold
Very little sympathy
He is a very lonely person
Has a nephew named “Kipper Krupp”
American Jewish
LOVES guacamole
Has an awkward crush on the lunch lady, Edith
Gets embarrassed when he realizes he’s in underwear
HATES fun
Very strict rules
Cartoonishly evil
GRUMPY, always angry or yelling
Very lonely

Whenever someone snaps their fingers, he becomes captain underpants, a childish, dumb, and heroic comic character due to the effects of the hypno ring: Throwing his clothes away leaving only his underwear, and ripping the red curtain of his office to make it a cape, saying “Tralalaaa…!”. However, when someone gets water on him he goes back to normal, and absolutely ashamed of being on underwear, confused because he doesn’t remember anything.

Mr. Krupp is a mostly bald, overweight man with a pear-shaped body and a piggish nose. As shown by the design of a dummy that resembles him, he has green eyes. Sometimes, when he laughs or becomes angry, his teeth grow sharp.

Benjamin covers his bald head with a messy, spider-like toupee. He wears an office shirt, a tie, and a pair of trousers.

In the book series, his clothes change color depending on the story. In the movie, Benjamin's tie is brown, and he wears green pants. Also, his white shirt has a pocket. In the Netflix series, he wears a purple tie and brown pants. There is also no pocket on his white shirt.

Benjamin "Benny" Krupp (better known as Mr. Krupp) is the principal of Jerome Horwitz Elementary School. He is the main antagonist of the franchise, though his alter ego Captain Underpants is the titular deuteragonist of the Captain Underpants franchise. He has a long history with two fourth grade students named George and Harold due to their constant pranks, wisecracks, and comic books. Mr. Krupp's alter ego is Captain Underpants, which he is totally unaware of.
Benjamin Krupp is an unbelievably arrogant, unsympathetic, rude, impolite, grumpy, egotistical principal. He distributes detention slips to any student for even a minor infraction, just so long as they are unfortunate enough to cross his path. In one case, Benny punished George and Harold by not allowing them to have cafeteria food and makes them bring their own lunches in his office to keep an eye on them, even though he had no actual proof (however, given that the two were responsible and their history of causing trouble it was justified). Benjamin once blackmailed George and Harold into doing all his daywork and even giving them extra homework in exchange for not getting "killed every day for the rest of their lives". He tore out the last seven pages of the book, "How The Grinch Stole Christmas", and to make the plot sound more realistic, assumingly cutting the book off right before the Grinch's heart grows.