This documentary is my oddest selection as far as traditional parameters of the horror genre are concerned, yet it's probably the one that best highlights what is most trivial in the average horror film.
What's more horrifying than people convincing themselves that learning how to efficiently obliterate life is part of the advancement of a greater good, and in doing so displace an entire people and poison their land for 40 years or more? Answer: realizing just who the real test subjects for these nuclear explosions were.
Radio Bikini also made my list because it contains a very unsettling reveal, about which I've already said too much.
One of the most suffocating films I've ever seen.