The first name of the author who created Harry Potter is Joanne.
J. K. Rowling was born Joanne Rowling on 31 July 1965 in Yate, Gloucestershire, England. She used the initials “J. K.” when the first Harry Potter book was published, partly because her publisher believed some readers might be less willing to buy a fantasy novel written by a woman.
The “K” was not part of her birth name. Rowling adopted Kathleen as a middle name for publication, honoring her paternal grandmother. Her full author name therefore became Joanne Kathleen Rowling, although she is most widely known professionally as J. K. Rowling.
A common mix-up is assuming that “J. K.” stands for a name she was given at birth. It does not. The Harry Potter series made the initials internationally recognizable, and Rowling later published crime novels under the pen name Robert Galbraith.