Again, there are so many great authors categorized under "C" that I can only highlight a few of them.
Suzy McKee Charnas is a founding member of Broad Universe and a winner of the Hugo, Nebula, and Tiptree awards. Unfortunately, I don't have any of her works in my collection, but you can find lists of her works on her website, Wikipedia, and Amazon.
C.J Cherryh is another well-known author and Hugo award winner. I think I've read the first book in her Foreigner series, but I'm more familiar with Rusalka and the sequels. Here are her Wikipedia and Amazon pages.
Jaleta Clegg is another member of Broad Universe. She's appeared on my blog, though I can't remember when. You can find a list of her works here and on Amazon.
One of my favorite SF authors is Julie E. Czerneda. I think she creates fantastic aliens, and I had the pleasure of meeting her at World Fantasy when it came to Madison. (At least, I think it was that con.)
I have more of her work beside the Species Imperative series shown here, including A Turn of Light. Here are the links for her website, Wikipedia entry, and Amazon pages.
Honorable mentions include Mona Clee, Flynn Connolly, and Leah Cutter.
Did I miss any women SF/Fantasy authors? Please feel free to mention them in the comments.