Rowling published two companion books to the Harry Potter series: "Fantastic Beasts and Where to Find Them" and "Quidditch Through the Ages", with proceeds going to charity.

Rowling wrote "The Tales of Beedle the Bard", a collection of stories mentioned in "Harry Potter and the Deathly Hallows". Initially, only seven handwritten copies were created, with one being auctioned for charity. It was later published for the general public in 2008.

Rowling published her first adult novel, "The Casual Vacancy", which received mixed reviews.

Rowling began writing crime novels under the pseudonym Robert Galbraith. The first book, "The Cuckoo's Calling", was initially well-received but gained significant attention when Rowling was revealed to be the author.

Rowling continues to write the Cormoran Strike detective series under the Robert Galbraith pseudonym, with multiple installments published to critical and commercial success.