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Principal Benjamin "Benny" Krupp (also known as Mr. Krupp) is the deuteragonist of the Captain Underpants series. He is the principal of Jerome Horwitz Elementary and the alter-ego of the superhero Captain Underpants.

In the film adaptation, he was voiced by Ed Helms, who also played Andy Bernard in The Office, the Once-Ler in the 2012 film adaptation of The Lorax, Number Two in Meet Dave, and Brad Gurdlinger in We're the Millers. In The Epic Tales of Captain Underpants, he is voiced by Nat Faxon. In the Japanese dub of the film adaption, he was voiced by Yatsunori Matsumoto, who also voiced Double in the Japanese dub of Mega Man X4.


Mr. Krupp is a very mean, sour, grumpy, bad-tempered, strict, sadistic, selfish, evil, angry and bossy principal who hates children, especially George and Harold, because of their constant pranks and rebellious behaviour.

However, his personality is completely polar as Captain Underpants. He's kind, jolly, loyal yet dim witted. Still he saves the day and is loyal to his sidekicks George and Harold.


Role in the books

One day, after George and Harold ruined a big football game, they were reported to Mr. Krupp's office the next day. Mr. Krupp showed them their pranks on tape and wanted to find out who was responsible for the fiasco. George and Harold pleaded that they did not want to be killed for the rest of their lives, so Mr. Krupp (who put up with them for years) blackmailed the two boys to do his chores and not smile or he will threaten to give the tape to the football team, essentially using them for child labor. He even sadistically asked their teachers to give them extra homework.

After enduring Mr. Krupp's punishments, George ordered a 3D Hypno-Ring which is delivered 4–6 weeks later after he and Harold suffered the brutal and intense punishment by Mr. Krupp. He and Harold then used it on Krupp to get him to forget about their punishments, such as giving the tape of George and Harold to George and Harold themselves and replaced it with Harold's little sister's video tape of Boomer the Purple Dragon (a spoof of Barney & Friends) sing-a long videos.

They proceeded to get Krupp to do ridiculous acts, culminating in making him believe he was their comic book creation, Captain Underpants. After pursuing Captain Underpants throughout the city and helping him defeat the villain Dr. Diaper, George and Harold managed to revert Krupp to normal by pouring water on his head before Mr. Krupp angrily tells the boys that he is going to give the tape to the football team. However, this had the side-effect of Krupp always transforming into Captain Underpants every time he hears someone snap their fingers.

Role in the film

In the film, Mr. Krupp is bent on busting George and Harold of their multiple pranks they had done to him and the other staff, though he finds it upsetting that he hasn't gotten any evidence to have them punished. He also hates their Captain Underpants comics as he forbids them from creating any in the school grounds, even tearing up their latest one detailing the origins of the superhero, much to their horror.

George and Harold's pranks come to an apparent end after they tamper with a toilet invention called the Turbo Toilet 2000 made by the school's local snitch Melvin Sneedly. With that in mind, Krupp happily decides to place George and Harold in separate classes in order to annihilate their friendship and their pranks. But before Krupp could fill up the paperwork to make it happen, George hypnotizes Krupp with a 3D Hypno-Ring he received out of a cereal box; the boys see that Krupp bears a resemblance to Captain Underpants without his toupee and command him to be Captain Underpants. However, this quickly backfires when Captain Underpants begins causing some problems around Piqua, thinking he is a real superhero with superpowers.

The boys discover that they can turn Captain Underpants back into Krupp by splashing water on him and can turn him back by snapping their fingers. Believing that Krupp will continue with his plan to separate them, they decide to settle with Captain Underpants but insist that he be dressed up as Krupp under the pretense of a secret identity, to which Captain Underpants agrees. His sudden personality change even manages to attract the attention and affection of the school's shy lunch lady Edith. The boys even learn (after exploring his house) that Krupp might not be as evil as they thought, but has rather been lonely for most of his life. Eventually, Krupp turns back into himself after a rainstorm occurred, learning that George and Harold have started a fair at the school without his knowledge. Having enough of their antics, Krupp angrily sentences the two boys to separate classes, much to their discomfort. Despite being satisfied that he finally punished the boys as promised, Krupp finds himself moping in boredom after looking at the casserole that Edith made for him, feeling so depressed that he never got a chance to ask her out on a date.

During the fight against Professor Poopypants and the Turbo Toilet 2000, the boys change Krupp into Captain Underpants to help them fight off the villains. Unfortunately, Poopypants gets the Turbo Toilet 200 to swallow Captain Underpants whole before taking George and Harold as hostages. However the boys' sense of comedy managed to help crash the Turbo Toilet's system, allowing Captain Underpants to escape after consuming the rotten leftovers inside. The leftovers also allowed Captain Underpants to obtain superpowers to finally defeat Poopypants, becoming a true hero to the public. However, George and Harold destroy the 3D Hypno-Ring in an attempt to permanently change him back into Krupp, as they knew that they can't control Captain Underpants. Feeling sorry for Krupp because he has no friends, the boys set him and the lovesick Edith up on a date. This made Krupp have a change of heart, even returning the comics he took away from George and Harold while admitting that they are funny.

However, the toxic waste from the Turbo Toilet 2000 transforms all the toilets into an army of Talking Toilets which attack the restaurant at which Mr. Krupp and Edith are dining. Upon snapping his fingers while calling for a check after seeing a toilet eating up a citizen in horror, Mr. Krupp once again becomes Captain Underpants, carrying George and Harold away to help him fight the Talking Toilets, which confuses George, as he thought destroying the ring would destroy the hypnotism.


  • In the books, Mr. Krupp did not reform and he remained being grumpy, mean and antagonistic unlike in films where he had change of heart near the end of the film, becoming less grumpy in the film.
  • The film gives Mr. Krupp redeeming qualities that are absent in the books: Here, he has a crush on Edith the lunch lady, his antagonistic traits are arguably a facade to hide his loneliness, and amused by the boys' comic about Captain Underpants, the latter fact which provide explanation on how he acts as his alter-ego to begin with.





  • Mr. Krupp transforms into Captain Underpants whenever he hears someone snap their fingers, and reverts back to normal when someone pours water on his head.
    • This even extends to being showered with kisses from Ms. Anthrope, as seen in the sixth book.
    • As seen in the eighth book, as long as water is on his head, he cannot transform into Captain Underpants.
  • Mr. Krupp is said to have been inspired by Dav Pilkey’s high school principal, who would reprimand Dav for drawing cartoons in class by telling him, “Artists are a dime of dozen, and you will never make a living as an artist, David.”
  • Despite his cruelty, Mr. Krupp does have a soft spot for his nephew Kipper, as he punishes anyone who seemingly bullies him, despite it being obvious that Kipper is the bully.
  • His full name, Benny Krupp, is a pun on the word "bankrupt."
  • His first name was first revealed in Captain Underpants and the Perilous Plot of Professor Poopypants.
    • Coincidentally, Professor Poopypants, the villain in that book, was the villain in the 2017 movie.
  • Mr. Krupp is occasionally fair to George and Harold. For example, in Invasion of the Naughty Cafeteria Ladies from Outer Space, he refused to punish them because the lunch ladies didn't have enough evidence to prove of their pranks, though he would change his mind and reprimanded them later on. Also, in Attack of the Talking Toilets, Mr. Krupp fears of losing his job due to the attack of the talking toilets, but George and Harold manage to get their robot to repair the school's damages, and Krupp cancels their suspension and places them as temporary principals for the day as a reward (although this could be attributed to desperation, since he would be held responsible for the damages.)
  • In Captain Underpants and the Sensational Saga of Sir Stinks-a-Lot, Mr. Krupp lost his ability to turn into Captain Underpants. The book stated that there are two possible reasons for this: the electromagnetic explosion that resulted from feeding Sir Stinks-a-Lot soda, Mentos, and pop rocks had erased the hypnotic spell from Mr. Krupp's brain, or Sir Stinks-a-Lot's Super-Power-Juice-ectonomy took away Mr. Krupp's superpowers.
  • Despite Mr. Krupp disapproving of the Captain Underpants comics, he knows exactly how Captain Underpants behaves, as evidenced by his near-exact impression of the hero while hypnotized. In the film, Mr. Krupp reveals that he has read the comics, which may be how he knows everything about Captain Underpants.
  • Dav Pilkey, the author of the book series, greatly approved Mr. Krupp's character development into a more likable character in the film that he wished to give the character the same development in his books back then.

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