J. K. Rowling has yet to write a book.
J. K. Rowling . Since then , Rowling has written four books for adult readers : The Casual Vacancy ( 2012 ) and -- under the pseudonym Robert Galbraith -- the crime fiction novels The Cuckoo 's Calling ( 2013 ) , The Silkworm ( 2014 ) and Career of Evil ( 2015 ) . She is the United Kingdom 's best-selling living author , with sales in excess of # 238M .