Which Harry Potter spin-off film series did J.K. Rowling write?

J.K. Rowling wrote the Fantastic Beasts film series.

The series began with Fantastic Beasts and Where to Find Them in 2016. Rowling wrote the screenplay, expanding a fictional Hogwarts textbook mentioned in the Harry Potter books into a story centered on magizoologist Newt Scamander.

The films are set decades before Harry Potter’s school years and feature locations and characters beyond the original novels’ British setting. The story moves through places including New York, Paris, and London, while also developing the history of Albus Dumbledore and Gellert Grindelwald.

The film series is different from the Harry Potter film adaptations, which were based on Rowling’s seven novels. Fantastic Beasts was created as an original screenplay series within the same wizarding world.