Enderman

Endermen are black, neutral mobs from the End that have the ability to teleport.

Spawning
Endermen spawn on solid blocks at light level 7 or less. They spawn commonly in the End in packs (or "hauntings") of 4. In the Overworld they spawn in groups of 1-4 and are rarer than most other mobs. In the Nether they spawn in groups of 4 and are rarer yet.

Drops
Endermen may drop 0–1 ender pearls (or up to 4 with the Looting enchantment), and 5 experience orbs when killed by a player or a tamed wolf.

Endermen holding a block will drop that block.

Behavior
Endermen do not attack unless provoked by a player attacking them or looking at their head from up to 64 blocks away. When provoked, endermen will open their mouths and shake with rage; when provoked by being stared at, they will also make a lengthy, loud, threatening sound and will run towards the player to attack. If an aggravated enderman is hit by another mob, it will cease attacking the player.

They can also step up one full block without having to jump.

Endermen are damaged by water and rain and will teleport away when they take damage from either of these. However, endermen do not take damage while standing in a filled cauldron. They will also teleport if they take suffocation, fire or lava damage, as well as damage from poison or the wither effect.

Endermen will continue chasing a player until they are either killed, sustain several hits, or become distracted by exterior elements like rain, fire, or sun; they are likely to teleport away to underground locations, such as caves and mineshafts, at day break. If the player sleeps in a bed, it is possible for an enderman to teleport on it and knock them off, however the player will continue sleeping.

Endermen cannot be provoked by players looking through transparent blocks or wearing a pumpkin on their head. However, they can become aggravated by a player in a minecart from some angles.

Endermen will attempt to kill endermites, provided they were spawned from ender pearls and there is no nearby player in Survival or Adventure mode. If the player is close enough to an endermite, endermen focus on the player instead of the endermite. Endermen can spot endermites from a distance of 64 blocks.

When under the invisibility effect, the enderman's body will disappear, but its eyes will still be visible. In the End, an invisible enderman at a distance will become visible as a pale purple silhouette.

Teleportation
When teleporting, for each attempt a random destination is chosen within 32 blocks along each axis (i.e. a 64×64×64 cuboid centered on the current position). It then seeks downwards (regardless of distance) from the chosen destination until the block below is made of a movement-blocking material. The teleportation attempt will succeed to that location as long as no liquid or solid blocks prevent them from standing there. Thus endermen typically need at least three non-solid blocks above the destination to successfully teleport. Exceptions are carpet that is not above a block made of a movement-blocking material and snow layers stacked 10 deep or more, as their materials are not flagged as blocking movement even though the blocks themselves do so.

Endermen always attempt to teleport upon taking damage, such as from water. Most ordinary melee attacks are successful, but are usually followed by an immediate teleport to a few blocks behind the attacking player. When directly attacked by the player, enderman have a chance not to open their mouths. Endermen cannot normally be attacked with projectiles in the PC version (including splash potions of harming), as they will always teleport away just before being hit. However, they will not teleport if positive potions are thrown at them, including splash potions of regeneration and strength, and will not teleport away from poison potions either. If all available blocks within teleport distance are removed or unable to be transported to, it is possible to hit endermen in the PC version with a projectile, arrows tend to bounce off dealing no damage on occasion. However, in the Console Editions, it is possible to hit an enderman with a projectile by arcing a shot onto the enderman without placing the crosshairs on them directly. When teleporting due to damage, an enderman will make up to 64 attempts to teleport.

An enderman cannot teleport while it is in a minecart, though in rain and water it will attempt to do so, always teleporting back into the minecart repeatedly until death.

Endermen will not teleport in the daytime while on soul sand unless they are damaged. They will also not teleport if attacked on their legs or by wolves, as wolves attack at the legs. Endermen also hardly teleport when combating other mobs like Iron Golems.

It is possible for an enderman to teleport at death. In PC edition, the ender pearl should drop as soon as the enderman dies, but the xp only appears as the enderman's body disappears. Because of this, it's possible to slay an enderman, pick up the pearl at the point where the enderman received the killing blow, and find the experience in the location the enderman teleported to.

Moving blocks
Endermen have a unique ability to pick up certain block types and move them around. They will pick up blocks in a 4×4×3 region horizontally centered on the enderman and vertically at the same level as the enderman itself. Endermen drop the block they are holding on death.

Endermen can only pick up the following blocks:

When carrying a block, the enderman may randomly place it, in a 2×2×2 region horizontally centered on the enderman and vertically at the same level as the enderman itself, if the target location is air with a non-air block beneath and the block is allowed to be placed at the target location.

While endermen may breach walls, bridge fences, break redstone circuitry, and even construct golems by removing or placing blocks, such actions are entirely random and not purposeful.

One can summon an enderman holding any block (including the ones not listed above) using the  NBT tag.

Data values
Endermen have entity data associated with them that contain various properties of the mob. Their entity ID is.

Trivia

 * Notch claimed in public that the enderman is a “subtle” reference to “the Slenderman”, a similar looking monster with a similar name. Given the later development of the End, it is possible he already had the name in mind, and did not choose it because of the Reddit thread in which their name was revealed.
 * In the Halloween texture pack for the Console Edition, the enderman is re-skinned to look like the Slenderman.
 * Enderman sounds seem to be reverse audios:
 * The "idle1" sound is a reversed “here”
 * The "idle2" sound is a reversed “hiya”
 * The "idle3" sound is a down-pitched “what’s up?” or “this way!”
 * The "idle4" sound is a down-pitched reversed “forever!”
 * The "idle5" sound is a reversed “uh oh!”
 * The collective noun for a group of endermen is “a haunting of Endermen”, as stated by Dinnerbone.
 * Switching to spectator mode and taking an enderman’s camera adds the invert shader, suggesting that they see the End as an island of blue cobblestone (because end stone is a yellowish inversion of cobblestone) in a white sky, with white pillars, white endermen with green eyes and a white ender dragon.
 * An enderman's eyes and body are located in two different texture files.
 * If directly attacked by a player (one hit only), Endermen have a chance not to open their mouths.

Beta 1.8+
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