Sarah Cawkwell
Sarah Cawkwell is currently the only female novellist in the sausage party that is the Black Library. The running gag is that she is a hot, sexy goth chick, because the only women who go into a Games Workshop are the ones that fa/tg/uys dream up in their heads. She's actually a rather charismatic but regular looking human being, who has a blog.
Not Aaron Dembski-Bowdenor Graham McNeill. Certainly not Nik Vincent, because that would mean that she'd be married to Dan Abnett.