From: Manhunt (PS2, Xbox, PC, 2003)

Manhunt's schlocky, low-fi take on horror was always creepy and unsettling, but things didn't get really scary until the end, when you were introduced to Piggsy. The chained, criminally insane pet of Manhunt's snuff-film-director villain Starkweather, Piggsy was an amalgamation of everything you'd never want to sit next to on a bus. Naked, morbidly obese and wearing a rotting pig's head as a mask, Piggsy hides in the shadows of the game's final level, waiting for the tell-tale sound of your footsteps - and then he'll jump out and start revving his chainsaw.

For such a fat bastard, Piggsy's awfully quick on his feet, and if you don't immediately start hauling ass to the nearest hiding place he'll kill you in seconds. At this point in the game, you'll have also lost all your weapons, so you're limited to whatever makeshift objects - like wooden stakes and shards of glass - that you can find laying around, and there aren't many of those. You'll also need to stealth-kill him multiple times - which only makes him run away in pain before going back on the hunt.

True, Piggsy's a pitiable creature, and once you know exactly how to dispatch him, he's not really that much of a problem to deal with. But until you do, you'll be running blind, trying desperately to stay alive long enough to escape from the waddling madman with the roaring chainsaw right behind you.

 
From: Clock Tower (PSone, 1997)

He looks a little silly now, but back when Clock Tower first appeared on the PSone, Scissorman was the most frightening thing we'd ever seen. Short, stooped and carrying a massive pair of garden shears, he'd slowly hobble after you, clanging his scissors together menacingly with every step.

It isn't Scissorman's appearance that makes him terrifying, though. While creatures like the Nemesis only show up at pre-determined points, Scissorman can show up anywhere, at any time. One minute you'll be exploring for a way out of your predicament, accompanied by no sound other than your own footsteps, and then all of a sudden his horrible, stress-inducing music starts playing. When that happens, it's your cue to run, and to keep running until you find a weapon or a flimsy hiding place. Once Scissorman's caught your scent, he won't stop chasing you until you've either given him the slip or let him have it with a can of mace.

Even if you do manage to find a place to hide, it won't guarantee your safety - especially if you use the same hiding place twice. Cowering under a desk or climbing inside a cardboard box might fool him once, but try it again and Scissorman will stab right the hell through whatever it is you think is protecting you. Also, you wouldn't always get a warning when he was on your trail. Sometimes he'd be hiding in a locker or behind a door, watching you and waiting silently for you to get close.

Making matters much, much worse is the fact that Clock Tower is a point-and-click game, meaning that your efforts to get away are dependent on you clicking a mouse cursor on something and hoping your sluggish avatar reacts quickly enough to avoid instant death. It's like one of those nightmares where your legs refuse to run away from the horrible monster, and even with crummy graphics and a cheesy horror atmosphere, it's still wicked scary.