Alien
what stayed with me in this film wasn't fear exactly, it was the feeling of isolation
the movie makes space feel cold asf and uncaring. The crew aren't heroes or chosen people. They're ordinary workers who happen to encounter something beyond their understanding, and that's what makes it unsettling. I also admire how restrained it is. The film trusts the audience's imagination. The movie doesn't need to constantly show the alien to make you nervous. It lets the tension build naturally until you're just waiting for something terrible to happen. Also, they should've just left the cat on earth.