I think it's more of a horror. The very idea of a re - animated corpse made from different body parts is a classic horror trope. The way the monster is often depicted as a menacing, unstoppable force is typical of horror. Although there is some science in the story about creating life, the overall tone and focus on fear make it horror.
I'd say Frankenstein leans more towards horror. The idea of a monster brought to life and the terror it causes is a classic horror element. But it does have some science fiction aspects like the concept of reanimating dead matter.
It could be either. It depends on the specific elements and themes presented in the work. Some extant works may have elements of both horror and science fiction.
Frankenstein is often considered both science fiction and horror. It has elements of scientific experimentation and creation, which are typical of science fiction, but the terrifying and monstrous aspects make it horror as well.
I recommend the following good horror science fiction novels to you: " The Period of Destruction: The Zombie Era ": A terrifying virus spreads and the end of the world arrives. Humans can only survive by cherishing the present. 2. [Wasteland Survival Diary: A wasteland world full of unknowns. The protagonist must change this world to survive.] These novels were all sci-fi horror novels. The plots were compact, full of excitement and horror. I hope you like it!
Here are a few good sci-fi horror novels to recommend:
1. [The Way of the Heavens]
2. [To Uncle Nine's Zombie World]
3. [Zombie Suppression System]
4. Doomsday Zombie Star Master
5. Zombie Husband, Be Good
6. Reborn Zombie Supreme
7. I'm refining zombies at the end of the world.
These novels were themed with horror, suspense, fantasy, and science fiction. They were suitable for readers who liked these kinds of topics. Please note that these recommendations are based on the search results provided. There may be other good sci-fi horror novels that have not been mentioned.