What is the first name represented by the “K” in J.K. Rowling?

The “K” in J.K. Rowling represents Kathleen.

Rowling was born Joanne Rowling and did not originally have a middle name. Before publication of Harry Potter and the Philosopher’s Stone, Bloomsbury asked her to use two initials because it believed a gender-neutral author name might appeal to boys as well as girls.

Rowling chose Kathleen, the first name of her paternal grandmother. She therefore became known professionally as J.K. Rowling, even though Kathleen was not part of her birth name.

The initial is often misidentified as Katherine because that is a more common spelling and is also used by other public figures. Rowling’s own explanation identifies Kathleen. Her later crime novels were published under the separate pen name Robert Galbraith, while her adult fiction The Casual Vacancy was published under J.K. Rowling.