Which 2007 Harry Potter novel was the first book in the series published simultaneously worldwide?

Harry Potter and the Deathly Hallows was the first Harry Potter novel published simultaneously worldwide.

The seventh and final novel was released on 21 July 2007. Its global publication strategy was designed to limit unauthorized copies and spoilers before readers could obtain official editions. The launch became a major international publishing event, with bookstores opening at midnight in many countries.

Earlier Harry Potter books were often released in the United Kingdom before their American editions. Deathly Hallows changed that pattern by coordinating publication across multiple markets. English-language editions appeared at the same moment, although local clocks meant that the event occurred at different local times.

The novel concludes Harry’s conflict with Lord Voldemort and brings together plot elements introduced throughout the series, including the Deathly Hallows themselves. It should not be confused with the two-part film adaptation, released in 2010 and 2011; the book itself appeared in 2007.