J.K. Rowling’s first name in her birth name is Joanne.
She was born Joanne Rowling on 31 July 1965. The initial “K” in her pen name does not represent a second given name she was born with. It was added by her publisher, Bloomsbury, before the first Harry Potter book was released.
The “K” stands for Kathleen, the name of Rowling’s paternal grandmother. Rowling adopted the initials partly because the publisher believed a gender-neutral author name might appeal more broadly to children, especially boys. She has also used the name Jo in personal and professional contexts.
The author’s legal and public naming history is often simplified in biographies. “J.K. Rowling” is the name associated with Harry Potter, while “Robert Galbraith” is the pseudonym she used for crime novels. Those names refer to the same author but serve different publishing identities.