Captain Underpants is an illustrated children's graphic novel series by American author and illustrator Dav Pilkey. The series revolves around two fourth graders, George Beard and Harold Hutchins, living in Piqua, Ohio, and Captain Underpants, an aptly named superhero from one of the boys' homemade comic books, who accidentally becomes real when George and Harold hypnotize their cruel, bossy, and ill-tempered principal, Mr. Krupp. From the third book onwards, Mr. Krupp also possesses superhuman strength, durability and flight as a result of drinking alien "Extra-Strength Super Power Juice".
 Currently, the series includes 12 books, two activity books, 15 spin-offs, coloured version and won a Kids' Choice Award on April 4, 2006. As of 2014, the series has been translated into more than 20 languages, with more than 80 million books sold worldwide, including over 50 million in the United States. DreamWorks Animation acquired the rights to the series to make an animated feature film adaptation, Captain Underpants: The First Epic Movie, which was released on June 2, 2017, to positive reviews.
 After the main series concluded with the twelfth novel, Captain Underpants and the Sensational Saga of Sir Stinks-A-Lot, in 2015, a spin-off series titled Dog Man was released the following year. The spin-off series has eleven books so far.
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 In book 11, when the teachers saw two Georges and two Harolds, they think they are dreaming and then they go naked. They are arrested when Miss Fitt pulled down Officer McWiggly's pants. Mr Hand in the series gets hired.
 The main series of novels has developed a pattern of alliteration from the fourth book on—except for the third book, whose "annoyingly long" title becomes a running joke in future books.
 Novels 6–12 in the main series form one unbroken story, in which the ending of each of such novel except the last is a cliffhanger, and the next novel in sequence immediately picks up where the last one left off.
 Dog Man is a comedic graphic novel series created by Dav Pilkey as a full spin-off book series to the Captain Underpants series. The series is about a dog-headed cop protecting the city he resides in with his friends. The series includes eleven books, the first released in 2016 and the latest in 2023. The latest book in the series is called Dog Man: Twenty Thousand Fleas Under The Sea and it was released on March 28, 2023.
 In 2020, ten Dog Man books (including one Cat Kid Comic Club, a spin-off) sold a total of over 3.8 million copies, 13% of the total comic book sales, as charted by BookScan. This does not include digital copies or any copy sold by Scholastic through school book fairs.
 These books have been released or announced so far in the series:
 The series has its own spin-off series titled Cat Kid Comic Club, with five books released:
 These books were reported "coming soon-ish" at the end of the books. No further information or cancellation has been released since their tease.
 According to the American Library Association, the Captain Underpants books were reported as some of the most banned and challenged books in the United States between 2000 and 2009 (13), as well as between 2010 and 2019. The books were named one of the top ten most banned and challenged books in 2002 (6), 2004 (4), 2005 (8), 2012 (1), 2013 (1), and 2018 (3). The Captain Underpants series was explicitly banned in some schools for "insensitivity, offensive language, encouraging disruptive behavior, LGBTQIA+ issues, violence, being unsuited to the age group, sexually explicit content, anti-family content, as well as encouraging children to disobey authority."
 The American Library Association stated in a release by the National Coalition Against Censorship that "This year's #1 banned book, Captain Underpants... is the gift that keeps on giving. Why? Because these popular, silly books are read by parents, with their children, all over the country. The toilet humor makes parents roll their eyes and kids giggle. The absurdity of banning books to attack perceived moral problems is exemplified by this year's winner."
 In October 2015, the 12th book received controversy due to a reference to Harold being gay. Some elementary schools have banned the book due to this.
 On March 29, 2021, Pilkey and Scholastic announced that The Adventures of Ook and Gluk would be ceasing further publication due to its use of passive stereotypes towards Asians, which Pilkey stated to be, despite unintentional, "harmful to everyone". Pilkey also announced that he would be donating all royalties from the book to organizations dedicated to stopping violence towards Asians and Asian-Americans.
 Although the first few books came out regularly, the ninth book, Captain Underpants and the Terrifying Return of Tippy Tinkletrousers (advertised in a teaser at the end of the eighth book), was not released until 2012, after a six-year wait. During this time, Dav Pilkey was caring for his terminally ill father, who died in 2008. In 2009, he signed a deal with Scholastic for four new books, the first of which was The Adventures of Ook and Gluk: Kung-Fu Cavemen from the Future, released August 10, 2010. The second was Super Diaper Baby 2: The Invasion of the Potty Snatchers, released June 28, 2011. The third book, Captain Underpants and the Terrifying Return of Tippy Tinkletrousers, was released August 28, 2012. The fourth book, Captain Underpants and the Revolting Revenge of the Radioactive Robo-Boxers, was released January 16, 2013.
 On October 20, 2011, it was reported that DreamWorks Animation had acquired rights to make an animated feature film based on the Captain Underpants series. On October 25, 2013, it was reported that Rob Letterman would direct the film, while Nicholas Stoller would write the script. It would have been the second film to have Letterman and Stoller working together, the first being Gulliver's Travels. On January 21, 2014, the cast was announced, with Ed Helms joining as Mr. Krupp/Captain Underpants; Kevin Hart as George Beard; Thomas Middleditch as Harold Hutchins; Nick Kroll as the insidious villain, Professor Poopypants; and Jordan Peele as Melvin, the nerdy nemesis of George and Harold. On June 12, 2014, the film was scheduled for release on January 13, 2017. Following DreamWorks Animation's reorganization in early 2015, the studio announced that the film would be produced outside of the studio's pipeline at a significantly lower cost. It would be instead animated at Mikros Image in Montreal, Canada, and it would look differently than most of DWA's films. A month later, Deadline reported that Letterman had left the project, and that David Soren, the director of Turbo, was in talks to direct the film, but Letterman returned to the project and served as an executive producer with Dav Pilkey. The film was expected to be released on March 10, 2017, but in September 2015, DreamWorks Animation's The Boss Baby took over its date. The film was released on June 2, 2017.
 On December 9, 2020, it was announced that a Dog Man feature film is in development at DreamWorks Animation with Peter Hastings directing at the helm after his experience with Dav Pilkey's works from The Epic Tales of Captain Underpants. On October 6, 2023, the movie was confirmed to be released in 2025.
  Dav Pilkey had looked to turn the books into a possible TV series, and he had imagined Chris Farley in the titular role. Around the same year the first book debuted to the public, Farley died of a drug overdose. Defunct animation studio Soup2Nuts also attempted to produce an animated series based on the books in the early 2000s.
 DreamWorks Animation Television produced a television series based on the film that was streamed to Netflix. It was released on July 13, 2018.
 In 2020, an interactive special called Captain Underpants Epic Choice-o-Rama was released on Netflix. The special involves Harold and George stopping Mr. Krupp from destroying their beloved treehouse.
 Censors in the United States have been targeting the Captain Underpants series after the first book was released in 1997. The Office of Intellectual Freedom of the American Library Association reported that Captain Underpants is the book series with the most complaints from libraries due to offensive content in the United States in 2012 and 2013. Several parents accused the book of having language inappropriate for the book's target audience, children enrolled in elementary schools.
 Jessica Roake, in an article published in Slate, argued that the books are well suited for young readers. She wrote that "They're drawn to them because for the first time in their reading lives they are understood, entertained, and catered to all at once. It is theirs, not ours, and that feeling of exclusive ownership forges the kind of connection everyone should have with at least one book in their life. For that, most every English teacher of my acquaintance will be more than happy to take the shot to the ego the Captain provides."
 The series has frequently been compared with the Horace Splattly series, but not always positively.