Which Harry Potter book did J.K. Rowling publish last in the main seven-book series?

Harry Potter and the Deathly Hallows was the last book in J.K. Rowling’s main seven-book series.

The novel was published on 21 July 2007. It follows Harry, Ron, and Hermione as they leave Hogwarts to search for Horcruxes and confront Lord Voldemort. The story resolves the central conflict that began with Voldemort’s attack on Harry as a baby.

Deathly Hallows is the seventh main novel, following Harry Potter and the Half-Blood Prince. Its title refers to three legendary magical objects: the Elder Wand, the Resurrection Stone, and the Cloak of Invisibility. The book’s publication ended the principal narrative arc, although Rowling later expanded the wizarding world through companion works, films, and other projects.

Harry Potter and the Cursed Child was published in 2016 as a script based on a stage play. It is set after the events of the seven novels, so it is not the seventh main Harry Potter novel or a replacement for Deathly Hallows.