Enderman

The Enderman is a rare mob that will be 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, open their mouth, 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. They will only teleport to somewhere you can see. Endermen can teleport about once per second. Endermen take damage from coming in contact with water (including water blocks and rain) and sunlight. Their exact size is 0.6x0.6x2.9.

Preventing Attacks
Wearing a pumpkin on your head, along with pressing F1 to hide the HUD, will prevent an Enderman to charge you. Having an Ender pearl in your inventory will reduce their maximum range to the half, and you will therefore be able to get a closer look. It is important to note that the Endermen will return aggresion if you attack them regardless.

Killing Endermen
Endermen are usually peaceful mobs untill they are threatened, or if you disturb them (by looking at their faces). So if you find yourself in this situation, here are some quick ways to keep yourself alive. Endermen are damaged by water, sunlight and other things. You can put a pumpkin over your head, then take them by surprise. Diamond Swords are a good suggestion, since they are quick and deadly. Water would be the best suggestion due to the fact that is keeps them from teleporting, and it kills them quickly. It's rather best to avoid the situation, than to engage one. This is just in case you find yourself in this situation.

Trivia

 * The name "Enderman" is a subtle reference to the popular internet phenomena Slender Man, and was given to the mob 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.
 * At the PAX Beta 1.8 demo, Endermen dropped diamonds.
 * Endermen occasionally emit black smoke-like particles. They appear to produce them when they are stared at, when moving, and when they teleport.
 * They may also produce a strange, croaky squark, however that may just be the background noise of the video.
 * Endermen have the ability to open their mouths. In their texture, their jaw is separated from their skull and in the 1.8 Official Trailer, an Enderman attacked the camera with its mouth open. This makes the Enderman the first mob with the ability to physically open their mouths without switching to a different texture. They only open their mouths when they attack. Due to the player's perspective, the player sees the back of the Enderman's head when they open their mouths. If a player is one block higher, they see through the Enderman's open mouth. They open their mouths by moving their skulls higher than their jaw. (Similar to the Canadians from South Park.)
 * In the 1.8 prerelease, Endermen sound like zombies, which is almost certainly a placeholder until the release when the real sound will download into the resources folder.
 * Endermen's eyes glow in the dark, like spiders'.
 * Endermen's full body glows in the fog. (Like Spiders)
 * Endermen seem to shake while you look at them.