Which Harry Potter book by J.K. Rowling is the longest in the original English series?

Harry Potter and the Order of the Phoenix is the longest book in J.K. Rowling’s original English Harry Potter series.

The fifth novel was published in the United Kingdom on 21 June 2003. Its first-edition English text contains 766 pages in the UK hardcover edition, making it longer than the other six novels in the original series. Page counts can vary between formats, countries and editions, but the fifth book remains the longest by word count in the standard English texts.

The story follows Harry’s fifth year at Hogwarts and introduces the secret group known as the Order of the Phoenix, which works against Lord Voldemort. It also features Dolores Umbridge’s appointment as Hogwarts High Inquisitor and High Inquisitor-style authority at the school.

Readers sometimes choose Harry Potter and the Goblet of Fire or Harry Potter and the Deathly Hallows because both are substantial books. However, Order of the Phoenix is the recognized longest installment in the original English sequence.