Which Harry Potter book did J.K. Rowling publish last?

J.K. Rowling’s last Harry Potter book was Harry Potter and the Deathly Hallows.

The novel was published on 21 July 2007. It is the seventh and final main book in the series, completing Harry’s struggle against Lord Voldemort. Much of the story follows Harry, Ron and Hermione outside Hogwarts as they search for Horcruxes.

The title refers to three legendary magical objects: the Elder Wand, the Resurrection Stone and the Cloak of Invisibility. Together they form the Deathly Hallows, although the book also continues plotlines involving Horcruxes and the history of Albus Dumbledore.

The film adaptation was divided into Harry Potter and the Deathly Hallows – Part 1 and Part 2, released in 2010 and 2011. The two films explain why the seven-book series produced eight films.