J. K. Rowling wrote a book.
Joanne Rowling , ( [ ˈrəʊlɪŋ ] born 31 July 1965 ) , pen names J. K. Rowling and Robert Galbraith , is a British novelist , screenwriter and film producer best known as the author of the Harry Potter fantasy series . They have become the best-selling book series in history and been the basis for a series of films over which Rowling had overall approval on the scripts and maintained creative control by serving as a producer on the final instalment .