J.K. Rowling’s first name in her birth name is Joanne.
She was born Joanne Rowling in 1965. The familiar form “J.K. Rowling” was created for the publication of Harry Potter and the Philosopher’s Stone. Her publisher asked for two initials because it was thought that some boys might be less likely to choose a fantasy book written by a woman if the author’s full name appeared on the cover.
Rowling did not originally have a middle name beginning with K. She adopted “Kathleen,” her paternal grandmother’s name, as a second initial for the author name. This produced the pen name J.K. Rowling, although she is often called Jo by friends and readers.
A common mix-up is treating “K” as part of her original birth name. It was added for publishing purposes, while “Joanne” is the first name recorded in her birth name. She later used the name Robert Galbraith for crime fiction, a separate pseudonym.