A Balrog is one of the more powerful creatures in the service of Sauron. The dark equivalent of wizards, Balrogs are creatures of shadow and flame, and originally served Morgoth, the master and mentor of Sauron. They were exceedingly powerful, and were as destructive and deadly as dragons. The chiefest and greatest of their race was their leader, Gothmog, who was slain by the warrior Ecthelion. The best known, Durin's Bane (later slain by Gandalf during the events of The Lord of the Rings), was one of the few Balrogs to survive the destruction of its kind in the War of Wrath during the First Age, in which Morgoth was captured and most of the Balrogs were killed.
Shadow of WarEdit
The Balrog who appears in Middle-earth: Shadow of War is named Tar Goroth, the only Balrog to obey Sauron. He will be a boss in the game, as one of Sauron's enforcers. He was awakened by his master when Talion and Celebrimbor forged the New Ring. He was a commander in Sauron's Army and was defeated by Carnan.