Deathwing

From wow.incgamers.com

Also known as Neltharion the Earth-Warder.

One of the Five Great Aspects, empowered by the mysterious Titans as the guardians of the tranquillity of Azeroth, Deathwing has been Lord of the Black dragons since Chaos was turned to Order, long before the Night Elves discovered magic and Sundered the world. The tale of Neltharion's fall is not entirely known, however it is believed that he turned on his brethren following the War of the Ancients.

Banding together with the Night Elves, the Five Great Aspects and their dragon-flights' faced the invasion of the Burning Legion. Neltharion convinced the four other Great Aspects that a weapon was needed to face the demonic threat. Each of the Aspects imbued a powerful artefact known as the Demon Soul with a portion of their essence, save for Neltharion who deceived his brothers and sisters. Once the Legion was rebuffed, Neltharion, perhaps now acquiring the name of Deathwing, turned on the other Aspects who had been weakened by their contribution to the Demon Soul. Uniting their diminished powers, the remaining four Aspects managed to bar Deathwing from using the weapon and drive him off.

Deathwing was not seen again until the Second War, when he reappeared even more fearsome then before. The insidious goblins had adhered plates of adamantine steel to his already impressive hide, making him nearly impervious to physical assault. Regardless, Deathwing was defeated by the Alliance forces and presumed dead until after the Horde had been defeated save for a few scattered clans.

The great black dragon reappeared once more, having assumed the disguise of one Lord Prestor of Alterac, using his dark magic to manipulate King Terenas of Lordaeron. Deathwing was also attempting to capture the imprisoned Alexstraza's eggs in an effort to procure a mate for himself. Eventually, with the aid of the other Aspects, the wizard Rhonin destroyed the Demon Soul and Deathwing was routed.

He reappeared for the final time when the heroes of the Alliance ventured through the Dark Portal into the world of Draenor. Deathwing was defeated, but it is unknown whether he escaped the devastation of that world or not.