of Moria > The Balrog of Moria
The Balrog of Moria - bearing no other name - this fallen Maiar served in the guard and armies of Melkor until the destruction of his evil master's realm at the end of the First Age. Fleeing the destruction and hiding from the searching Ainur, he was sealed in a deep tomb beneath the long spine of the Misty Mountains. After thousands of years, he was accidentally released in Third Age 1980 by Dwarves mining for the precious metal, Mithril. Once unleashed from his subterranean prison, the Balrog quickly slew two Dwarven kings, Durin VI and his son Nain I. Gathering an army of orcs, he drove out the Dwarves from their beloved home in only one year. The Balrog remained master of Moria for many years, even slaying Balin and his company in Third Age 2989 - 94, and was only vanquished in Third Age 3019 during the War of the Ring by Gandalf, who also perished (temporarily) in the struggle.
References: Lord of the Rings, Silmarillion