Harry Potter and the Deathly Hallows sold 2.65 million copies in the UK on its first day.
The seventh and final Harry Potter novel was published on 21 July 2007. Its launch followed years of worldwide interest, and booksellers organized midnight openings so readers could obtain copies as soon as the publication embargo ended. The reported first-day UK sales made it the fastest-selling book in British publishing history at that time.
The figure refers to the United Kingdom, not worldwide sales. International sales were reported separately, and the book also set major records in the United States. That distinction matters because global and national totals are often combined in casual summaries.
Deathly Hallows concludes Harry’s conflict with Lord Voldemort and resolves the series’ central mysteries. It was divided into two films, but it remained one novel, published in a single volume in 2007.