J.K. Rowling adopted the middle name Kathleen when she became a published author.
Her birth name is Joanne Rowling. The initial “K” does not represent a middle name given to her at birth; Rowling chose Kathleen in honor of her paternal grandmother, Kathleen Ada Bulgen. Her publisher requested a second initial before the first Harry Potter book was released, and she became known professionally as J.K. Rowling.
The author has explained that the name was selected partly because publishers believed a gender-neutral presentation might appeal to readers of different genders. The books were therefore marketed under initials rather than the first name Joanne, although the author’s identity was not permanently hidden.
The name should not be confused with “Joanne Kathleen Rowling” as a birth name. Kathleen was adopted for her author identity, while Joanne is her given first name. The initials became one of the most recognizable author brands in contemporary publishing.