The A-Z Blog Challenge is cruel in that a wonderful, beautiful day like April 28 tends to end up with the toughest letter of them all, X. (I may be a bit biased about April 28, given that it's my birthday.) The next time I do this challenge, I'll go backward to avoid this problem. The letter "X" is such a difficult match that I couldn't think of a woman SF author with an X-name and had to resort to a series title: Xenogenesis, by Octavia Butler. (I mentioned in my B entry that I was saving her for a strategic use; this is it. Technically, this series has been republished as an omnibus edition called Lilith's Brood, but that title won't help me with this challenge.)
Butler was another notable writer who won both the Hugo and the Nebula. Strangely enough, the Xenogenesis series (consisting of Dawn, Adulthood Rites, and Imago) didn't win these awards, and it wasn't nominated for them either. Each book in the trilogy was nominated for a Locus Award but didn't win that either. This is a shame, as this series features aliens with a very useful third gender. (The ooloi, as the third-gendered aliens are called, have the ability to manipulate DNA.) As the ooloi exchange DNA with humans, whom they consider too violent to be left alone as a species, we question what gender and human nature are. I recommend the read.
As for Butler, I was surprised to learn that she struggled with dyslexia. However, she started writing when she was ten years old, so she had plenty of time to master her craft. I've read the Parable series but only one of her Patternist books. Learn more about Butler on her official website and Wikipedia, and find her work on Amazon.
The letter "X" can also stand for the X chromosome that is doubled in women, or it can stand for all the unknown women writers who never got published because of their gender or had to hide it behind initials or male pseudonyms. But if anyone can name me a female SF/fantasy writer with an "X" name (no, Xena doesn't count), I'll be happy to award you one of my eBooks for free. Just provide the link below in the comments.