Enderman

The Enderman is a mob that was introduced in version 1.8; The Adventure Update. The Endermen are 3 block high black creatures with long arms and legs,as well as glowing purple eyes, and they emit purple particles similar to a Nether portal. They are rare in comparison to other mobs, with the exception of the Cave Spider. 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, and when they get close enough they teleport behind you, so beware. 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
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, ice and vines - but not stacked half slabs.

Endermen will not attack players who are wearing a pumpkin. A good idea is to make a texture pack with no pumpkin blur.

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.

Damage to Structures
Endermen can pick up almost every "building" block (not torches, beds, chests, furnaces, etc). This includes bedrock, obsidian, and diamond blocks.

Because Endermen possess the ability to move blocks, they can cause damage to player built structures by breaking and replacing blocks, which they appear to do in a random fashion. Stone and sandstone are commonly moved, as opposed to wooden plank blocks. Endermen also appear to possess the ability to break glass blocks and occasionally place glass as well. Endermen can also hold brown mushrooms. This may become quite a problem as regards the security of player built structures against hostile mobs, whereby an Enderman makes a hole in a wall or window and subsequently a creeper sees the player through the hole and thus engages it. Since Endermen can't pick up stairs, a suggestion for keeping Endermen from destroying walls is to make them out of stairs. To stop this from affecting the look of the wall, cover the bits where the stairs show with normal blocks. Another suggestion would be to surround your house with a moat, this can be done with either water or lava as both damage the Endermen.

Bugs

 * Endermen do not drop the block they're holding when killed or despawned.
 * If an Enderman picks up a block with a tile entity, such as a chest, its contents will be deleted.
 * In survival mode, Endermen can pick up and place bedrock.
 * When using a custom texture pack, Endermen will be bright white overlapping their texture.
 * Endermen appear to spawn into well lighted areas
 * Endermen do not appear to be rare, they spawn really often, and even in groups of 5.
 * When your crosshairs on on the Enderman, and it is still frozen, you can hit it from an extended distance than normal reach.

Trivia

 * If a Skeleton shoots an Enderman when attempting to shoot the player the Enderman will completely stop chasing the player even after it has killed the offending Skeleton.
 * 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 actual 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.
 * As of now, enderman sound like zombies, but that is a place holder, new sounds were made, but not yet implemented
 * 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.
 * What Notch wrote in his first official discription of the Endermen, "-the feeling of control", may have meant more than it appeared, referencing a deeper fear in players, the fear that they now had something closer to an equal, and thus something to challenge their control.