The End is an alternate dimension from the Minecraft Universe and is the one dimension in Minecraft with the least amount of mobs.
The End is the third dimension in Minecraft that is made up of a material called End Stone. It is supposedly a lost planet or comet, or a piece of another world knocked off by a powerful force. It is populated by Endermen, Shulkers, and the Ender Dragon. The other two dimensions of Minecraft are The Overworld, the main dimension where the player spawns, an infinite world of grasslands, deserts, tundras, oceans, etc, and The Nether, a hellish realm underneath.
One of the most popular species found in The End. They are tall, black skinned, creatures with purple eyes and the ability to teleport between The End and the Overworld.
The possible ruler over The End, the Ender Dragon, was a massive dragon that drew power from Ender Crystals.
A species of crustacean-like creatures that lived in large obsidion towers that have a similar appearance to a clam from Earth.
http://aliens.wikia.com/wiki/Endermite Endermites are a purple insect-like species native to the End. They sometimes appear when an Enderman teleports, or when an Ender Pearl is used.