|“||The Dwarves delved too greedily, and too deeply. You know what they awoke in those mines: shadow and flame.||„|
|~ Saruman alludes to Durin's Bane.|
Durin's Bane, also known as the Nameless Terror, is a supporting antagonist in J.R.R. Tolkien's novel, The Lord of the Rings, and in the film trilogy based off of it, appearing only in The Lord of the Rings: The Fellowship of the Ring.
This particular Balrog, whose name was unknown, is a Balrog that fought with Morgoth's armies during the First Age under the command of Gothmog. However, Morgoth's armies were defeated, and most of the Balrogs were killed off. Durin's Bane went into hiding in the deep places of the world with few other Balrogs that had survived the First Age (for this Balrog, Moria).
Eventually, while hiding in Moria, it was accidentally awakened by the Dwarves in Moria, who delved too deeply into the mines in their insatiable appetite for more precious Mythrill. Upon awakening, the Balrog killed or drove out the Dwarves with all speed.
In TA 3019, the Fellowship of the Ring are forced to enter Moria. The Balrog discovers them, scares off the Goblins surrounding the Fellowship, and follows them to the bridge of Khazad-dum. The Fellowship of the Ring make it across the bridge, but Gandalf stays behind, and prevents the beast from crossing, shattering the Balrog's sword. He uses his magic staff to break the bridge, but as Durin's Bane falls into the chasm below, it wraps its fiery whip around Gandalf's legs, and drags him down with it.
After a long fall, Gandalf and the Balrog crash into a huge underground lake, which extinguishes the flames of the Balrog's body, leaving it severely weakened and forcing it to retreat from the wizard. Gandalf then pursues the beast for several days, chasing it out of the tunnels and onto the highest peak of the mountains of Charadras, where its flames explode back to life. The Balrog is eventually defeated and cast down onto the mountain side, dead. However, this is only the Balrog's physical body, so its spirit's fate is unknown.