"K" SF women kick butt!
I'm most familiar with Mary Robinette Kowal's Glamourist Histories novels (set in an alternate Regency where magic works), but she has also written novellas and short stories. (The covers for her print books are much more attractive than what I have here!) She's won two Hugos and the John W. Campbell Award. She was vice-president of SFWA in 2010, but I don't think she still holds that position. Learn more about her and her work on her website, Wikipedia, and Amazon.
Nancy Kress is best known for her work Beggars in Spain. (I've read the entire trilogy.) She writes everything from short stories to novels and won a Nebula for Best Novella in 2012. Her work focuses on genetic engineering and artificial intelligence. You can learn more about this accomplished author on her website and Wikipedia and read her books on Amazon.
Ellen Kushner was a Guest of Honor (along with her wife, Delia Sherman) at the second WisCon I attended. She writes mannerpunk such as Swordspoint and its two sequels. She's also run programs for the Online Writing Workshop for Fantasy, Science Fiction, and Horror, though I don't remember taking any classes from her during my time in OWW. Learn more about her on her website and Wikipedia and read her books on Amazon.
Feel free to add more "K" SF women authors to this list in the comments below.