James Tiptree, Jr.
J.K. Rowling wasn’t the only one who was told to take a male pen name because no one would take her seriously in science fiction/fantasy without it. There’s been a long tradition of women taking male pen names to be accepted in these genres, James Tiptree, Jr. (Alice Bradley Sheldon) is just one of the best. Here’s only one of her gigantic catalog of awesome stuff. Again, a WayBack selection, so excuse the poor visuals.
More online fiction and biographical resources can be found at https://en.wikipedia.org/wiki/James_Tiptree,_Jr.