SF And Horror

Satan's World.

Horror intersects with fantasy, sf and realistic fiction:

ghosts or vampires;
Frankenstein monsters or Body Snatchers;
cannibals or serial killers.

Some people's idea of sf might be just its horror element:

Frankenstein;
Quatermass;
Doctor Who's monsters.

There is a nightmare quality to some passages in William Dexter's Children Of The Void and also to Chapter XVI of Poul Anderson's Satan's World - Falkayn, holding down the plunger of a grenade, not only confronts a monstrous Minotaur-like alien but also moves closer to that being in order not to be trapped on the wrong side of a bomb-proof barrier where he could be killed by a robot. Many people would be inclined to escape from this situation merely by removing their thumb from the plunger...