What middle name does J.K. Rowling use in her full name?

J.K. Rowling’s middle name is Kathleen.

Her full name is Joanne Kathleen Rowling. She was born Joanne Rowling, but the initials “J.K.” became her public author name when Bloomsbury prepared the first Harry Potter book for publication. The publisher reportedly wanted initials rather than a clearly feminine first name to appeal to boys in the target readership.

Rowling did not originally have a second given name. “Kathleen” was added in honor of her paternal grandmother, Kathleen Ada Bulgen. That family connection explains why the K appears in her author name even though Rowling’s birth name was Joanne Rowling.

The author is often called “J.K. Rowling,” although she has also published adult crime novels under the pseudonym Robert Galbraith. The initials should not be expanded as “Joanne Kathleen Rowling” without context: the name is correct, but the K was adopted as a middle name for publishing purposes rather than being part of her original birth name.