J.K. Rowling’s surname before her marriage to Jorge Arantes was Rowling.
She was born Joanne Rowling, and she continued to use Rowling professionally. After marrying Portuguese television journalist Jorge Arantes in 1992, she was sometimes referred to as Joanne Rowling Arantes. The marriage ended in divorce in 1995.
The initials J.K. were not her original full name. Her publisher requested two initials for the author name, and Rowling used “K” for Kathleen, her paternal grandmother’s name, although Kathleen was not part of her birth name. The resulting author name became J.K. Rowling.
The name “Joanne Murray” is also associated with Rowling’s later family life, because she married Neil Murray in 2001 and has used different forms of her name in biographical contexts. For books, however, Rowling remained the public author surname, making the biographical distinction important.