What author is well known for writing speculative fiction and featured cover art by her brother on one of her books?
The Goblin Mirror:  It was first published in a hardcover edition by Ballantine Books under its Del Rey Books imprint, and featured cover art by Cherryh's brother, David A. Cherry. C. J. Cherryh: Carolyn Janice Cherry (born September 1, 1942), better known by the pen name C. J. Cherryh, is an American writer of speculative fiction.
C. J. Cherryh