Which Harry Potter novel is the longest in the English-language series by original edition page count?

Harry Potter and the Order of the Phoenix is the longest Harry Potter novel by original English-language edition page count.

The British hardback edition contains 766 pages, making it the longest of the seven novels in its original English editions. The story follows Harry’s fifth year at Hogwarts and introduces the student group known as Dumbledore’s Army, formed to practice defensive magic while the Ministry of Magic denies Voldemort’s return.

The novel was published in 2003, three years after Harry Potter and the Goblet of Fire. It also introduces Dolores Umbridge as the Ministry-appointed Hogwarts High Inquisitor and explores Harry’s connection with Voldemort through the prophecy and the Department of Mysteries.

Page counts can vary by country, format, type size, and edition. That is why comparisons should specify the original English-language editions rather than treating every paperback or translation as identical. Within the commonly cited British hardback figures, Order of the Phoenix is the clear longest book.