Enderman

The Enderman is a rare mob that was introduced in version 1.8; The Adventure Update. The Endermen are depicted as 3 meters tall, black creatures with long arms and legs, glowing purple eyes, and emit purple particles similar to a portals. They also have the ability to pick up and move blocks around. They are generally peaceful. However, if a player looks at them by placing his or her crosshair directly over them, they freeze, stare back at the player, open their mouth and become hostile. They stay frozen as long as the player continues to look at them. When the player looks away, they will quickly run towards the player; if they are a long distance away, they will teleport several times until close enough to reach the player. They will only teleport to somewhere that is visible to the player. 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 the head will prevent an Enderman from charging at a player. It is important to note that the Endermen will become aggressive if players attack them. It is safe to look at them through transparent blocks like glass, glass panes, iron bars and ice.

Killing Endermen
Despite their appearance, Endermen are easier to kill than most other mobs, since they are damaged by water, sunlight, fire, lava and attacks alike. Emptying a bucket of water on the ground may be useful in confined spaces, as you can damage the Enderman with the water and your attacks at the same time. Arrows and all types of sword are effective against one, though wood and stone swords may not deal enough damage to kill the Enderman before it kills you. It is possible to kill an Enderman by looking at it, keeping its gaze, and shooting arrows at it until it dies.

Bugs
There is a report of Endermen not responding when the players look at them in multiplayer in the 1.8 pre-release.

Trivia

 * The plural of “Enderman” is “Endermen”.
 * The name "Enderman" has been interpreted by some as a reference to the Internet meme known as "the Slender Man", a similar-looking fictional cryptid. The name was given to the mob by Notch in a Reddit thread.
 * Due to the similarities to the Slender Man, 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; in the pre-release they drop a unique item called an Ender Pearl.
 * 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.
 * In the 1.8 pre-release, Endermen sound like zombies, which is almost certainly a placeholder until the release when the real sound will download into the resources folder. ( Endermen still sound like zombies in 1.8.1)
 * 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.
 * When you pause the game, the Enderman will keep shaking.
 * A possible origin of the concept of the Endermen could be "The enigma of amigara fault"
 * In the final release of 1.8, the Enderman's eyes are now purple, and instead of emitting smoke they emit nether portal particles.