Anyone who has woken, sweating, from a nightmare where something sinister is chasing you knows the fear of the emotionless, ruthless killer that just keeps going, like an evil Energizer Bunny.
It doesn't matter where or how fast you run; it will find you. A distinct character type from the serial killer or slasher, these aren't your standard horror fare. They'll have a reason, a mission, maybe even their own code of ethics. But it's useless trying to appeal to their better nature for mercy. These antagonists are incapable of sympathy and will singlemindedly see their plans through to the bitter end, while remaining coldly indifferent.
Whether artificial, supernatural or just plain human with a big old dollop of celebrates the movie menaces who can't be bargained with, can't be reasoned with, don't feel pity, or remorse, or fear… and absolutely will not stop, ever, until you are dead!
