What's the true origin story of the Balrog from The Lord of the Rings? Alongside orcs, dragons, and ents, the Balrog is one of the most memorable fantasy creatures glimpsed in The Lord of the Rings. A demonic, fiery beast wielding a whip of flame, the Balrog infamously catches the Fellowship during their tense escape from the Mines of Moria. Gandalf risks his life trying to fend the creature off, and narrowly averts death by reincarnating into Gandalf the White, but their battle made the Balrog iconic, despite being only a fleeting addition to Tolkien's trilogy.
J.R.R. Tolkien would adapt the Balrogs over the course of his writing. Between The Fellowship of the Ring and The Silmarillion, Balrogs differ in rarity and strength, and their true nature switches from the monstrous to the divine. The Balrog encountered in Moria is specifically known only as Durin's Bane - a title that hints at the greater story lurking behind this formidable monster.
When Gandalf confronted Moria's Balrog, the two opponents couldn't been less alike in physical terms. In truth, however, the Balrog and Gandalf were once both of the same ilk. Like Gandalf, the Balrogs began as primordial spirits known as Maia, who had existed since before time began and took no physical form. Where Gandalf was incarnated as a wizard and sent to Middle-earth along with a select few companions (Saruman, Radagast, etc.), some of the Maiar were swayed to evil by Morgoth - the first real enemy of Middle-earth. As one of the Valar, Morgoth outranked the Maiar, and those who fell under his control were corrupted, taking on the monstrous, fiery form seen in The Lord of the Rings. The Balrog's origin closely follows Christian mythology, where the angels who chose to follow Lucifer ultimately became demons.
Among Morgoth's earliest servants, the Balrogs were present in Middle-earth long before the Ring was forged, long before the time of men, and even before the arrival of the elves. While their master was kept prisoner by the other Vala, the Balrogs slept in the pits of Angbad, only to be awakened by the cry of Morgoth's return to Middle-earth, at which time they resumed their servitude, waging war against elves and men. During these ancient times, the Balrogs were led by Gothmog, but when Morgoth was defeated in the final year of the First Age, they retreated into the dark depths once again, and this is how Durin's Bane came to be in Moria.
The total number of Balrogs in Tolkien mythology is somewhat contentious. At times in The Silmarillion, Tolkien suggests a host of Balrogs are under Morgoth's command, but the author's son Christopher later confirmed that only a maximum of 7 ever existed. Being such rare specimens, Durin's Bane undoubtedly would've been present during those ancient historic battles, but without Morgoth, he remained undisturbed in Moria until the arrival of the dwarves. As they are wont to do, the dwarves' greed led them too deep into the mines, and their hammering disturbed the Balrog for the first time in millennia. While most would run for their lives, the people of Durin stood their ground, and were soundly defeated. Had dwarves not already awoken the beast sleeping in Moria's depths, it's unlikely that the presence of nine fleet-footed Fellowship members would've roused it. Gandalf destroyed the physical form of Durin's Bane but, as a Maia, the Balrog didn't die in the traditional sense.
Like many characters in The Lord of the Rings, the Balrog is deceptively important to the history of Middle-earth. What might initially appear to be a simple cave-dwelling fire monster, the Balrog is one of the oldest creatures the Fellowship encounter, and was present at so many of the important battles that shaped Middle-earth's future. One fascinating tidbit not addressed in The Lord of the Rings is how Sauron cannot (or will not) call the remaining Balrogs to action, despite also being a fellow servant of Morgoth, and this proves how powerful the demonic spirits truly were.
