Thaurlach

Thaurlach was one of the Balrogs that survived into the Third Age.

The Lord of the Rings Online
He was among the Balrogs that survived the War of Wrath and were ordered to hide until further orders. He fled to The Rift of Nûrz Ghâshu, but was followed by an elf-maiden Glathlírel who was determined to end him. He eluded her for millennia, until she was able to face him in combat and defeat him. Rather than kill the Balrog, the two Blue Wizards decided to imprison him in the Rift, so that he could await his judgment at the end of days. However, by the end of the Third Age his chains were loosening and a band of players was sent to defeat the weakened Thaurlach - something, that as Gandalf remarked, should have been done ages ago.

Appearances
The Lord of the Rings Online