Balrogs, also known as the Valaraukar, were Maiar that were seduced and corrupted by Melkor into his service.
Originally, in unrecorded ancient times, the Balrogs were fiery Maiar that were persuaded by Melkor's might and splendor to join his cause. Their first dwelling was in [], but after their master's defeat during the [for Sake of the Elves|War for Sake of the Elves], the Balrogs and other creatures in Melkor's service escaped to [].
Years of the Trees
Balrogs were present as early as the [of the Trees|Years of the Trees] when Melkor and [] went to [] and destroyed the [Trees of Valinor|Two Trees]. By then, the Balrogs remained in the pits of Angband. After Morgoth destroyed the Trees with [], he came to the ruins of Angband to renew his rule in Middle-earth. A disagreement with Ungoliant led to her attacking him, and Morgoth gave out a great cry that roused the Balrogs from their slumber. In a tempest of fire, the Balrogs drove Ungoliant away and prepared to pursue her. However, they were halted by Morgoth and returned to Angband, which shortly thereafter was constructed anew.
When the [] won the battle [], [] furiously pressed on toward Angband. He came even within sight of Angband, but was ambushed by a force of Balrogs with few Noldor around him. Soon he stood alone, but long he fought on with all Balrogs alone as mightiest all the [of Ilúvatar|Children of Iluvatar] even though he was wrapped in fire and wounded with many wounds. But finally [(Balrog)|Gothmog], Lord of the Balrogs, felled and mortally wounded Fëanor.
[], Fëanor's son, persuaded the forces of Morgoth for a feigned treaty, but Morgoth sent his Balrogs. The entire company was slain, except for Maedhros, who was later brought to Angband.
Years later, during the [Bragollach|Dagor Bragollach], the Balrogs, along with [] and an army of [], were issued forth from Angband to assault the fortresses of the Elves and to kill their allies, the [].
The Balrogs fought during the [Arnoediad|Nírnaeth Arnoediad], where Gothmog led the invasion. He threw aside [] and [], turned upon [] and killed him with the help of another Balrog, securing the field for Morgoth's forces. He also captured Húrin, after Húrin was buried under a mountain of slain foes. He bound the human warrior and delivered him to Angband, whereupon Morgoth attempted unsuccessfully to pry the location of [] from him.
In [510|FA 510], during the [of Gondolin|Fall of Gondolin], the Balrogs rode upon the backs of dragons to reach the hidden city of []. The Lord of the House of the Fountain, [of the Fountain|Ecthelion], managed to kill Gothmog at the cost of his own life. While attempting to escape the burning city, [] and his companions were blocked by another Balrog. To save [], [] and their young son [], Glorfindel fought the Balrog on a cliff and cast it down, but he was pulled down with the Balrog to their deaths.
The remaining Balrogs fought in the [of Wrath|War of Wrath]. While most were destroyed, some managed to escape and hide in Earth's deep caverns.
In [1980|TA 1980], a Balrog awoke in [] when the [] had mined too deep for []. It drove the Dwarves out of their home and slew King [VI|Durin VI], and the Balrog was thereafter called "[Bane|Durin's Bane]".
During the [of the Ring|War of the Ring], the [of the Ring|Fellowship of the Ring] passed through Moria and encountered Durin's Bane, which pursued them to the [of Khazad-dûm|Bridge of Khazad-dûm]. [the Grey] fought the Balrog, allowing the Fellowship to escape Moria. Both fell into the abyss, but the [of the Peak|battle continued at the peak of Zirakzigil]. Finally, it ended, but both Gandalf and Durin's Bane were slain in the process. Gandalf was later "sent back" by the Valar, as Gandalf the White.
[] generally took the form of tall, menacing beings roughly humanoid in shape, though seeming to consist of or be surrounded by shadow and flame. They used both a flaming [], and a fiery whip; they were constantly burning, and their weapons appeared molten. Gothmog, the Lord of Balrogs in the First Age, used a black ax as well.
It is unclear, and highly debated, whether Balrogs had wings.
Balrogs seemed to encapsulate and project power and terror, perhaps meant to be a dark shadow of the majesty that the [] radiate. Additionally, [] refers to Balrogs with "streaming fiery manes".
Additionally, they may have been able to alter their body structures on occasion, as in the battle between [Bane|Durin's Bane] and Gandalf, when the Balrog fell into a body of water he shifted himself into something slimy. However, it is also possible that this alternate form was simply Gandalf using colorful language to describe what the Balrog was like after having its flame extinguished and being covered in water. It is also possible that, while the Balrog, like all other [], could shift form, this was not a case of that.
Powers and abilities
Balrogs were exceptionally powerful creatures. Only seven [] were required to drive away [], a large monster powerful enough to devour the fruits of Telperion, which produced the light for billions of stars.
A single Balrog, who became known as [Bane|Durin's Bane], managed to drive the [] of [] from their ancient and supremely fortified nation-state, which was at the time the greatest kingdom of Dwarves that had ever been. It also contended with [], and shattered the side of a mountain with physical might alone. The Balrogs were considerably bodily agile, such that their passing is once described as a “tempest of fire”.
[] fought against and overcame [], an elf who was powerful enough to control the light of the two trees. He also spread chaos through the city of [], filled with elves of similar, though far lower, caliber. It was even thought to be at least somewhat comparable to [] during the first age.
In [], the word Balrog means "Demon of Might", from the words bal ("power") and raug, rog ("demon"). Balrogs are called Valarauko or Valaraukar in [], from the words vala ("power") and rauco ("demon").
In other writings, Balrog is derived from ñgwalaraukô ("demon").