The Ender Dragon 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.
Before entering The End, it is very strongly advised that the player first sleep in a bed near the end portal, in case he/she dies during the battle.
Upon entering The End, a purple "boss health bar" appears at the top of the player's screen. This bar indicates the remaining health of the resident Ender Dragon. Each End dimension houses a single Ender Dragon whose health is periodically charged by nearby Ender Crystals. These crystals can be found at the top of Obsidian pillars which dot the landscape. The healing effect of the Ender Crystals can reverse hard-won damage rather quickly, therefore it is recommended that they be destroyed before the player engages the Ender Dragon (arrows may bounce off silver bits of wings).
Destroying an Ender Crystal while the Ender Dragon is being charged by it (indicated by a series of circles appearing between the Ender Crystal and the Ender Dragon) will cause the Ender Dragon to take additional damage instead of being healed (You can destroy an Ender Crystal by either trying to destroy it as you would a regular block, or by attacking it with a sword, a bow and arrow, etc.) When destroyed, the Ender Crystal explodes and is replaced by a block of Bedrock.
The most common and easiest strategy to defeat the Ender Dragon is to destroy all Ender Crystals before attempting to fight the Ender Dragon, as any damage done to the dragon will be reversed. An advisable strategy for this (since Ender Crystals explode), is to shoot arrows from a distance so the player does not damage themselves, and then climb up the Obsidian towers with a ladder, thus ensuring that if the player falls off the tower due to exploding Ender Crystals, they will be able to grab onto the ladder and not die (although watch out as the Ender Dragon can and will destroy your ladders).
The Ender Dragon will flee when looked at, except when charging the player, but otherwise will fly directly at the player. When the Ender Dragon is charging the player, it is directly facing the player, giving the player a good chance of attacking its head, which, will do extra damage (but if you do decide to attack it, you will have less time to try and avoid its attack). The Ender Dragon will also destroy any block it comes into contact with except Obsidian, End Stone and Bedrock (passing through them instead), making TNT strategies difficult if not impossible to successfully execute. Due to the Ender Dragon's speed and flight, projectiles are favored over melee approaches. The Ender Dragon's immense health and evasive nature necessitate a large ammunition stockpile. Lava is useless, as they are immune to fire damage. Water is also useless, as they take no damage from water and will destroy the block. Knockback enchantments will also do nothing. Snowballs have the potential to stun-lock an Ender Dragon as its recovery time is slower than the firing rate of snowballs. The Ender Dragon will take more damage from a melee attack than a ranged attack, thus waiting for it to charge, sidestepping, and then attacking is a viable tactic. Beds, which explode in The End, can be detonated when the Ender Dragon is nearby, causing it considerable damage. Ender Dragons take the most damage from damage dealt to the head. Hitting other areas of the body will not do as much damage.
Once killed, the Ender Dragon will appear to have beams of light spontaneously erupting from its body. It will then explode, dropping enough experience to bring a player from no experience to level 110 (20000 - 10 drops of 1000 experience, one drop of 10000 experience). If you bring an enchantment table and 30 bookcases with you while killing the Ender dragon, you can set it up after it dies and use it every 50 levels for many level 40+ enchantments. It will also spawn a Dragon Egg on top of an End Portal made of Bedrock. On the second block up, two Torches are placed on either side. Entering the portal will activate a very lengthy (Average of 8 minutes, 30 seconds) text cutscene that acts as the end of Minecraft, after which the player will be teleported to their spawn point in The Overworld. This cutscene can be skipped by pressing the Escape key, and will instantly send you to your spawn point/Bed in The Overworld. The player may return to The End after defeating the Ender Dragon, however there will be no new dragon.