Harry Potter is a series of seven fantasy novels written by British author J. K. Rowling. The novels chronicle the lives of a young wizard, Harry Potter, and his friends, Ron Weasley and Hermione Granger, all of whom are students at Hogwarts School of Witchcraft and Wizardry. The main story arc concerns Harry's conflict with Lord Voldemort, a dark wizard who intends to become immortal, overthrow the wizard governing body known as the Ministry of Magic, and subjugate all wizards and Muggles (non-magical people).

The series was originally published in English by Bloomsbury in the United Kingdom and Scholastic Press in the United States. A series of many genres, including fantasy, drama, coming-of-age fiction, and the British school story (which includes elements of mystery, thriller, adventure, horror, and romance), the world of Harry Potter explores numerous themes and includes many cultural meanings and references. Major themes in the series include prejudice, corruption, madness, love, and death.

Since the release of the first novel, Harry Potter and the Philosopher's Stone, on 26 June 1997, the books have found immense popularity and commercial success worldwide. They have attracted a wide adult audience as well as younger readers and are widely considered cornerstones of modern literature, though the books have received mixed reviews from critics and literary scholars. As of February 2023^[update], the books have sold more than 600 million copies worldwide, making them the best-selling book series in history, available in dozens of languages. The last four books all set records as the fastest-selling books in history, with the final instalment selling roughly 2.7 million copies in the United Kingdom and 8.3 million copies in the United States within twenty-four hours of its release. It holds the Guinness World Record for "Best-selling book series for children."

Warner Bros. Pictures adapted the original seven books into an eight-part namesake film series. In 2016, the total value of the Harry Potter franchise was estimated at $25 billion, making it one of the highest-grossing media franchises of all time. Harry Potter and the Cursed Child is a play based on a story co-written by Rowling. A television series based on the books is in production at HBO.

The success of the books and films has allowed the Harry Potter franchise to expand with numerous derivative works, a travelling exhibition that premiered in Chicago in 2009, a studio tour in London that opened in 2012, a digital platform on which J. K. Rowling updates the series with new information and insight, and a trilogy of spin-off films premiering in November 2016 with Fantastic Beasts and Where to Find Them, among many other developments. Themed attractions, collectively known as The Wizarding World of Harry Potter, have been built at several Universal Destinations & Experiences amusement parks around the world.

The series follows the life of a boy named Harry Potter. In the first book, Harry Potter and the Philosopher's Stone (Harry Potter and the Sorcerer's Stone in the US), Harry lives in a cupboard under the stairs in the house of the Dursleys, his aunt, uncle and cousin, who all treat him poorly. At the age of 11, Harry discovers that he is a wizard. He meets a half-giant named Hagrid who gives him a letter of acceptance to attend the Hogwarts School of Witchcraft and Wizardry. Harry learns that his parents, Lily and James Potter, also had magical powers and were murdered by the dark wizard Lord Voldemort when Harry was a baby. When Voldemort attempted to kill Harry, his curse rebounded, seemingly killing Voldemort, and Harry survived with a lightning-shaped scar on his forehead. The event made Harry famous among the community of wizards and witches.

Harry becomes a student at Hogwarts and is sorted into Gryffindor House. He gains the friendship of Ron Weasley, a member of a large but poor wizarding family, and Hermione Granger, a witch of non-magical, or Muggle, parentage. The trio develop an enmity with the rich pure-blood student Draco Malfoy. Harry encounters the school's headmaster, Albus Dumbledore; the potions professor, Severus Snape, who displays a dislike for him; and the Defence Against the Dark Arts teacher, Quirinus Quirrell. Quirrell turns out to be allied with Voldemort, who is still alive as a weak spirit. The first book concludes with Harry's confrontation with Voldemort, who, in his quest to regain a body, yearns to possess the Philosopher's Stone, a substance that bestows everlasting life.

Harry Potter and the Chamber of Secrets describes Harry's second year at Hogwarts. Students are attacked and petrified by an unknown creature; wizards of Muggle parentage are the primary targets. The attacks appear related to the mythical Chamber of Secrets and resemble attacks fifty years earlier. Harry discovers an ability to speak the snake language Parseltongue, which he learns is rare and associated with the Dark Arts. When Hermione is attacked and Ron's younger sister Ginny Weasley is abducted, Harry and Ron uncover the chamber's secrets and enter it. Harry discovers that Ginny was possessed by an old diary, inside which the memory of Tom Marvolo Riddle, Voldemort's younger self, resides. On Voldemort's behalf, Ginny opened the chamber and unleashed the basilisk, an ancient monster that kills or petrifies those who make direct or indirect eye contact, respectively. With the help of Dumbledore's phoenix, Fawkes, and the Sword of Gryffindor, Harry slays the basilisk and destroys the diary.