Almost every single horror game is capable of creating truly monstrous creatures, but there are very few enemies that fill players with a real sense of dread. Being afraid of something is one thing, but actively avoiding it is another realm of real, palpable fear.
Enemies that are some fearsome, so ruthless, and so dreaded that players will turn and walk in the opposite direction as opposed to every contend with them. The enemies that are genuinely terrifying and whose presence is enough to reduce you to a quivering wreck. Monsters that ruin that sense of calm collectiveness and simply cause sheer and utter panic.
Surprisingly enough, a lot of these enemies appear in non-horror games. In games where the explicit function of the game is not to scare. Which makes encountering these foes all the worse. Because even when you are a badass warrior, armed to the teeth, there are certain things you just don't mess with.
You can try and act brave, but having to contend with these enemies is enough to give anyone a full-on aneurysm.