The 13 Masters of Evil
Lady Arabella is the elven queen and has been for many, many years. She resides deep inside the elven kingdom and isn’t seen by outsiders, or even most of her people. The elven kings (of whom there are seven) do her bidding, and have been rewarded with immortality for their service.
In the Ruins of Cilox there is evidence to suggest that the demon Viell is actually a descendant of hers. If this is true, it would mean that she has been alive since well before the First Great War. If that information became public knowledge, the dwarven and human kingdoms would almost certainly begin a war against the elves.