We are used to seeing and processing human faces and objects, but seeing an eerie, near-human image such as a zombie triggers fear. The face we see technically has all the features that should make it recognisable to us as a human  but instead we are faced with something feral, lacking humanity.

1 Stalkers - Dead Space Series\n\n They are not indestructible like the Hunter but they are even scarier. They are like the velociraptors of Necromorphs: very fast, deadly, and heart attack-inducing. They are another zombie breed that lets out a loud and shocking scream when they attack.