Durin's Bane

Durin's Bane" refers to the particular Balrog of Morgoth that had fled following the War of Wrath to dwell deep within the depths of the Dwarven kingdom of Khazad-dûm. Although its true name and particular history are unknown, this Balrog eventually became an important figure during the War of the Ring after being awakened by the Dwarves of Khazad-dûm.
== Background ==
Durin's Bane was the last of the Balrogs. His true name was never revealed. Living in the mines of Moria, the Balrog was awaken from his slumber when the Dwarves dug to deep in the mines. The Balrog destroyed Durin III, causing his people to retreat from Moria. Ancient people had dubbed it Durin's Bane and none dare to enter the mountain.
== The Lord of the Rings: The Fellowship of the Ring ==
Many centuries later, the balrog is woken up from its slumber after Pippin Took inadvertently alerted the enemy and Durin's Bane of their presence. It began pursuing the Fellowship all the way to the Bridge of Khazad-dûm, where Gandalf confronted the creature to protect the fellowship so they could make their escape. Durin's Bane brought Gandalf down along with it. 
=== The Lord of the Rings: The Two Towers ===
Gandalf and the Balrog  entered a battle for two days when Gandalf finally killed the beast, and the Balrog was no more,