For whose who wonder how broad and how deep the presence of women writers in these genres, here are some useful lists:

http://www.tfrohock.com/blog/2015/4/5/199-womenwritefantasy  (The list is now somewhere over 240 and we know it's not complete.  There's a crosslink to the list below, and to two other lists; you'll note incomplete overlap, which is typical.   The list concentrates on fantasy, but many of the writers on it also write, or wrote, science fiction.) 

http://elspethcooper.com/blog/archives/2204  (cross linked to the list above.)

The impetus for these lists is the consistent use in media stories about fantasy (in books, movies, TV shows) of male writers as exemplars.  There's nothing wrong with listing Tolkein, Pratchett, Gaiman, and Martin...but that's not the whole story even for male writers, and certainly not the whole story when female writers aren't even mentioned (not even J.K. Rowling.)  The groundswell of fantasy that began in the 1960s with Tolkein and others was soon so full of women writers that some of the male writers were furious--their turf was being invaded (and those books were selling like hotcakes.)   Women writers would like to see enough media mention of women writing fantasy and science fiction--lists that put books by men and by women side by side, without any coy commerntary--so that new readers coming into the field would know they existed.   When woman-written fantasy is mentioned at all, it's often on a very narrow base and with presumptions about content that do not hold up to examination. 

Women write all kinds of fantasy, all kinds of science fiction.  They write books with both male and female protagonists.  They write books with and without romantic relationships in them.  They write books with and without overt violence in them.  They write books with hard-science concepts, and books that ignore science.  Some write elegantly, stylistically equal to any literary novel.  Some go to the heart of  the story, writing more casually.  So, of course, do men.  You cannot tell, from the sex of the writer, what the book will be...without reading it.    So here are lists to explore, or--if you already know this and are occasionally asked "Are there any women who write this stuff?", you now have a link to point them to.