Dragons were introduced in Minecraft Sol Edition 1.2.
The Nether Dragon spawns in the End. Its main attack is flamethrower. So far it cannot be tamed. It's hostile.
The Aqua Dragon spawns in caves under ocean biomes. Its main attack is whirlpool (Middle Button). It is tamed with raw fish, and cannot fly. Passive.
The Undead Dragon is a rare spawn. It does not burn in sunlight. It is hostile and is untamable. Its main attack is to summon a hoard of zombies.
The Cave Dragon is a hostile dragon. It spawns in caves and its main attack is to ignite stone. It is tamed with Slimeballs.
The Artcic dragon spawns in the arctic and is passive. It is tamed with Polar Bear Meat, and its main attack is to freeze the air into ice.