Her real name is Nelle
In honor of a grandmother named Ellen, Harper Lee was given the name Nelle, which she grew up going by. Nelle is the name Ellen spelt backwards.
So why was Harper Lee, rather than Nelle Lee or Nelle Harper Lee, given credit for To Kill a Mockingbird? Lee apparently didn't want to risk the possibility that people would confuse the names Nelle and Nellie. As a result, Harper Lee wrote her first book, and her second book will be published under the same name.