J.K. Rowling’s first name is Joanne.
She was born Joanne Rowling on 31 July 1965 in Yate, Gloucestershire, England. The initial “K” in her pen name does not represent a second given name she was born with; it was chosen later for publishing purposes.
Rowling has explained that her publishers wanted a name that might appeal broadly to readers, including boys, and suggested using initials. She added “K” in honor of her paternal grandmother, Kathleen Ada Bulgen, creating the name J.K. Rowling.
A common mix-up is calling her “Joanne Kathleen Rowling” as though Kathleen were part of her birth name. Kathleen is associated with her pen name, while Joanne is the name given at birth. She has also published crime novels under the name Robert Galbraith, a separate pseudonym.