A Balrog is a fictional creature from J. R. R. Tolkien's Middle-earth world.
Balrogs were were originally made by Morgoth from corrupted Maiar. They appeared as great fiery creatures. Most of the Balrogs were destroyed in the War of Wrath at the end of the First Age. In 1980 of the Third Age, the Dwarves woke a Balrog deep in the mines of their home Khazad-dûm. The Balrog killed their King Durin VI, earning it the name Durin's Bane; Khazad-dûm was subsequently deserted, later becoming known as Moria. The Balrog of Moria was killed by Gandalf the Grey in 3019 T.A..
The Sindarin name Balrog is a translation of the Quenya name Valarauko ("Demon of Might", plural Valaraukar).