Which Harry Potter novel was the first J.K. Rowling book to be published simultaneously worldwide?

Harry Potter and the Deathly Hallows was the first J.K. Rowling book published simultaneously worldwide.

The seventh Harry Potter novel was released on 21 July 2007 at 00:01 British Summer Time. Publishers coordinated the international launch to reduce the period in which unofficial copies, spoilers and unauthorized translations could circulate before readers received authorized editions. The release became a major global publishing event.

The novel concludes the central conflict between Harry Potter and Lord Voldemort. It follows Harry, Ron Weasley and Hermione Granger as they leave Hogwarts to search for Voldemort’s Horcruxes. The book also explains the significance of the Deathly Hallows, three magical objects linked to an old wizarding tale.

The simultaneous launch followed increasingly large release events for earlier books. Deathly Hallows sold millions of copies immediately and was later adapted into two films, released in 2010 and 2011. The final book’s publication date is different from the date when Rowling completed the manuscript.