Balrog

A Balrog is a corrupted Maia from the Lord of the Rings continuum. It is an ancient evil fire-demon, and only the most powerful can stand against it (for example, Glorfindel and Gandalf).

There have been Sues who slay Balrogs, and even Sues who are Balrogs (sweet, kind, misjudged Balrogs). Neither of these are at all likely. Balrogs are dangerous. Many Sues have been fed to the Balrog that lived in the Mines of Moria, however.

Mini-Balrogs are just like their Middle-earth counterparts, only about one-twentieth of the size and somewhat less dangerous; at the least, not guaranteed to try to kill their owners, or Agents would not use them as pets.