C.L. Moore's "Shambleau" was published in the November 1933 issue of Weird Tales, a well-regarded pulp magazine that also published authors like Lovecraft and Burroughs. Since I love the old science fictiony pulps, I knew I'd end up enjoying this tale. C.L. Moore was a woman, and many who wrote in those times used their initials to get around the bias of the editors. It was her very first professional sale.
Moore's "Shambleau" is a Western set on Mars. It made me think of one of my old Ace Double novels that had a very similar concept, including an alien that was reviled and looked down on by the interlopers from the other planets. I have a sneaking suspicion that author had read this story when they were younger.
Everything from a stock Western is here, from a gunslinger with a gray reputation to a damsel in distress, except with more cat attributes. The town is filled with the usual trope characters, and there's some odd forbidden romance in the air.
The thing that makes this a science fiction instead of a Western is the alien that is inseparable from the story. There is a good smattering of horror, from the description of the creature to what it was able to do to others. The town knows what the alien is and wants to kill it. The protagonist takes the poor thing under his protection. Unlike many Westerns, however, he lives to regret his choice. Moore shows us how something, an "other", can sometimes come with severe, life-threatening consequences. Since we can look back with a historical lens, perhaps it was created from the culture that saw interracial or same-sex couples as something terrible. Indeed, many hapless others were killed because of who they chose to be with. The twist for this line of thinking was the alien was actually something that was deadly and dangerous, especially since it brought in some mythology of the Gorgon and Medusa.
The story covers things like the alien being a sexual predator, who uses her tentacled head to wrap others in a sexual dream state while she drains them of life energy. Think of Toby Hooper's movie Lifeforce except with no naked Mathilda May and more tentacles on a fuzzy catwoman. A side effect of the alien's power is she makes her "food" feel addicted to the feeling of sexual prowess that can overcome the revulsion of what she's doing.
Overall, a good read that is right in line with the pulps of the era.