J.K. Rowling’s first name is Joanne.
She was born Joanne Rowling on 31 July 1965. The initial “K” was added by her publisher before the release of Harry Potter and the Philosopher’s Stone because the publisher believed that a name with two initials might appeal broadly to readers, especially boys.
The “K” represents Kathleen, the first name of Rowling’s paternal grandmother. Rowling did not originally have Kathleen as a middle name at birth; it became part of the author name used publicly.
She is often called Jo by friends and in informal contexts. The spelling Joanne is also sometimes incorrectly written as Joanna. The author name J.K. Rowling became the enduring public brand associated with the Harry Potter novels, while her later crime books used Robert Galbraith.