Acnologia

Acnologia, also known as The Black Dragon of the Apocalypse, is an extremely powerful dragon that flies around the continent or world. It once faced Fairy Tail's strongest Mage, Gildarts, in battle, and was said to have instantly defeated him, tearing out several organs in the process. Acnologia's power is such that even the most evil and powerful Mage in the world, Zeref, fears him.