3. Necromorphs - Dead Space
In space, no-one can hear you scream. Well, except the Necromorphs. These guys were the enemies of the player in atmospheric horror
Dead Space, which left me sleeping with the lights on for about a week. Necromorphs are reanimated corpses who have been reshaped by an extraterrestrial infection and their sole purpose is to spread this infection. They are extremely aggressive and won't hesitate to attack you on sight. They may be seen as mindless killing machines but they are all under control of the Hive Mind so they do share some degree of cooperation with each other. Much like a colony of ants or bees. What really set your pulse racing in
Dead Space was the fact that the Necromorphs could not be dispatched by conventional means. You had to literally dismember them limb from limb to ensure that they did not come back looking for round two. Being chased by these guys down the tight, winding corridors of the Ishimura and realizing you didn't have enough ammo was more than enough to have you reaching for the off button out of sheer panic and fear.