Enderman

The Enderman is a mob introduced in version 1.8; The Adventure Update. The Endermen are depicted as 3 meter tall, black creatures with long arms and legs. They also have the ability to pick up and move blocks around. They are generally peaceful. If you look at them, by placing your crosshair directly over them, they freeze, stare back at you, and become hostile. They stay frozen as long as you keep looking at them. When you look away, they will quickly run towards you; if they are a long distance away, they will teleport several times until close enough to reach you. Endermen can teleport about once per second.

Trivia

 * The name "Enderman" is coincidentally close to that of the Slender Man, a similar-looking fictional cryptid (a mysterious, rarely-seen paranormal being along the lines of Bigfoot or the Mothman). Its name was given by Notch in a Reddit thread.
 * Due to the Slender Man similarities, many have petitioned to change the name "Endermen" to "Far Landers". Notch has stated however that he will not change their name, regardless of this petition, going as far as to joke that he should change the name of the Far Lands to "The End" instead.