Notch has already seriously cut into our sleeping time simply by creating Minecraft, but with this new, horrific mob we'll be lucky if we sleep one wink per week. Notch's "Endermen" were designed specifically to creep players out -- to not only be scary, but to be gut-twisting terrifying. In his blog post, "The psychology of the reticle and the feeling of control," Notch describes how he created the Endermen and what they will do to raise your heart rate:
"Suddenly you could walk up to these looking beasts (they're three meters tall) and watch them as they moved their blocks around, but as soon as you happened to look straight at them, they'd attack. And by 'straight at them', I mean putting the reticle on top of them. You can keep them visible on screen and actually look straight at them in real life, but as soon as your in game character looks straight at them, boom.

"Still, that was more scary than creepy.... I wanted something a bit more psychological. So to really drive home the point of looking at them being bad, I made the Endermen freeze and turn towards you when you look at them. As long as you look straight at them, they stand perfectly still and look straight at you. As soon as you look away, they will run (very fast) towards you.

"And they teleport."
The Endermen will begin stalking Minecraft with the Adventure Update, but if you can't wait, check out the inspiration for the creatures' name, Slender Man.

http://www.joystiq.com/2011/07/30/th...ft-mob-update/