J.K. Rowling used the initials J.K. as her author name. Her birth name is Joanne Rowling, and the middle initial was chosen for the publishing of the Harry Potter series.
Rowling has said that she did not have a middle name when she was young. Her publishers wanted a name that might appeal broadly to readers, including boys, and suggested using initials rather than her first name. The K stands for Kathleen, her paternal grandmother’s name.
The name is sometimes mistakenly expanded as “Joanne Kathleen Rowling” as though Kathleen had always been part of her legal birth name. Kathleen was adopted as a professional middle name for publication. Rowling has also used other author identities: she published The Casual Vacancy under her familiar name and crime novels under the pseudonym Robert Galbraith.
The initials became internationally recognizable through the Harry Potter books, whose covers commonly credit the author as J.K. Rowling. Her later publications have retained the same public author name.