Joanna Russ. I thought she was particularly good as a short story writer.
From The Nation magazine, comes an article that's worth a read: "Why Science Fiction Is a Fabulous Tool in the Fight for Social Justice," by Laura Flanders. It's an interview with the two editors of Octavia's Brood, "an anthology of radical science fiction by activist writers."
It was news to me that Mumia Abu Jamal is a Star Trek fan:
I had the honor of visiting him on death row. I made some Star Trek reference and Mumia just flowed with it—he was like, "Right? Live long and prosper." Mumia is a nerd in all ways; he really sees the visionary realities and possibilities of science fiction. He contributed an essay on Star Wars, US imperialism, and militarism, and also recorded an audio version. It's amazing to hear him not only give this brilliant analysis but also do a Darth Vader impression.
Certainly science fiction can be a good vehicle for leftist ideologies, but it works for all sorts of other ideologies, too. Libertarian science fiction is a thing.
Joanna Russ did an essay years ago on why Star Trek is better (i.e., more politically progressive than Star Wars. Of course, it was a smart piece — it was written by Joanna Russ — but alternatively it could be read as an example of the dangers of politicizing everything.
Hat tip for the Nation article: Ted Hand.