Ender Dragon

The Enderdragon is the first official boss mob to appear in Minecraft. It only naturally spawns in The End. This mob uses the Dragon model Notch created, but utilizes a texture more reminiscent of an Enderman, being black and scaly with purple eyes. Like other dragons, the Enderdragon will have 6 limbs; consisting of 2 wings, 2 legs and 2 arms.

Strategy
When entering The End, the player will notice a Boss health bar on top of their screen, indicating the health of the Enderdragon. Enderdragons can be found flying around The End nearby the Obsidian pillars, periodically being charged by Ender Crystals on top. The Enderdragon can destroy all blocks, including Bedrock, except End Stone and Obsidian, which they pass through harmlessly. The player will have to destroy a majority of the Ender Crystals in order to kill the dragon unimpeded. As they explode when destroyed, and how precarious they are located, it is advised to destroy them from a distance with a projectile, such as arrows, snowballs, or eggs. The most effective way to kill one is by use of Bow and Arrow, although it is advised to have a large stock of arrows, as Enderdragons are difficult to hit and have a large amount of health. Once killed, a unique death animation will occur to one, spawning a fountain-like Bedrock End Portal that will return the player to the Overworld. They also drop a very large amount of experience, useful for Enchanting. On top of this portal is a Dragon Egg, which teleports if clicked on by the player. Entering the portal will play the ending to Minecraft, afterwards returning the player to their spawnpoint.

History
Originally, dragons were a possible planned mobs hinted at by Notch during the Spider Jockey update. He also mentioned that dragon lairs may be an addition. They remained a potential work-in-progress until the Enderdragon was announced.

Notch has, in the past, stated that if dragons are added, they will not be able to be mounted because it would put pressure on servers in SMP.

In September 2011 Notch stated that "dragons will be added eventually".

On October 7th 2011 Notch revealed the existence of the Enderdragon.

On October 10th 2011 Notch released a video showing a small clip of The End which also shows the Enderdragon fly into the top of the frame. 

On October 11th 2011 A player named stropping_notch asked Jeb if Dragon riding is an idea, to which he replied it is. It is not clear whether this means it is an idea under consideration or not, however, or whether it would apply to the red Dragons or the Enderdragon.

On October 12th 2011, in a Reddit post Notch also said, "They will be different dragons. The Enderdragon will probably become larger, and the ones in the main world will be this size, won't go through terrain, and will be red because dragons are red."

On October 12th 2011, in a twitter post Notch also said: "Dragons have 6 limbs" Which would consist of 2 wings, 2 legs and 2 arms.

On October 13th 2011, Beta 1.9 Pre-release 4 was released along with The End. The Enderdragon exists in the code, mostly functional, however the dragon had not been enabled ingame yet. A community-made mod allows players to spawn Enderdragons by parrying with a golden sword.

On October 27th 2011, Beta 1.9 Pre-release 5 was released and Enderdragons could finally be hurt. They still do not seem to appear naturally in The End and need mods or a mob-spawner to be brought into the game. However, when slain, it has a very distinct death animation: it will rise upwards, emit purple beams of light from its body while the body itself disappears pixel by pixel, until it's all gone, and the lights fade away. They dropped a block of Obsidian along with their large amount of experience. Their bodies also deflected arrows.

On November 11 2011, Beta 1.9 Pre-release 6 was released and Enderdragons could finally spawn in The End.

Trivia

 * The name "Enderdragon" was first made known through a tweet by Notch reading "raqreqentba," which could be decoded using the ROT13 cypher, translating to "enderdragon."
 * According to Notch on Reddit, there will only be one Enderdragon in the End.
 * The Enderdragon has its own separate mob folder containing separate designs; the old gray skin and the newer black skin.
 * Made of 61 cuboids, the polycount on the dragon is higher than all models in Minecraft. Notch joked about how Minecraft was "going next gen" when deadmau5 mentioned this.
 * Before it was textured, Notch reported how he was afraid to texture it as it was a complicated model. In the end, the dragon model was so complex Notch reported that he gave up making the texture manually and invented a texture packer tool to aid him in adding the texture to the model. Notch also uploaded the code for the tool so others could use the pack.
 * As of 1.9 Pre-release 6, Enderdragons:
 * No longer catch fire from lava or the fire aspect enchantment.
 * Can only be hurt below the 127 block map height limit. Getting Enderdragons to fly above the limit (in Creative Mode, Overworld) will prevent any damage that could be done to them.
 * Have their own achievement called "The End" which requires defeating an Enderdragon. However, this has been tested and the achievement does not seem to work even if the player defeats the Enderdragon.
 * In terms of how difficult the Enderdragon will be to defeat, Notch tweeted that his design guideline for the dragon is "If I can beat it at all, it's too easy."
 * On October 12 2011, Notch uploaded a video showing why Enderdragons will not spawn in the main world, as they will destroy any block they come into contact with.
 * On Reddit, Notch explained why Enderdragons destroy matter.
 * When an Enderdragon destroys a block by means of flying through it, an explosion effect occurs and is identical to that of a TNT explosion.
 * When hit, it makes the same pain sounds as the player.