The Underdark

Those who dwell on the surface know very little of the races that make The Underdark their home.  They are only spoken of in hushed tones, as most are considered evil and there are fears that one day they will emerge into the light of the sun to take over the surface world.  Those fears are not completely unfounded, as the more prominent of the races of Underdark are the dark elves known as the Drow, and the Duegar, or dark dwarves, both of which have no love for their distance cousins on the surface, or any other race, truth be told.
Luckily for the rest of the world, both are typically so preoccupied with their own petty obsessions that they really haven't posed a threat so far.  The Drow constantly fight among themselves, jockeying for favor within the court of their dark queen, often with plans to take her power should the opportunity present itself.  This game of intrigue takes place with their massive city of Ulteran, although it often spills out into the Underdark at large, but so far has not managed to make its way to the surface.
Meanwhile, the Duergar focus their efforts on taking what they can from their distant relatives, the dwarves.  This can take the form of simple raids on supply lines to outright attacks on the underground cities or mines of their cousins.  Unfortunately for them, the dwarves always seem to have the upper hand and forced the Duergar to retreat further and further into the depths of Underdark.  This has served to just stoke their hatred of the dwarves even more.
Other common races include the Svirfneblin, or deep gnomes, the strange and violent Derro, and the universally feared Illithids, or Mind Flayers.  While the vastness of the Underdark holds a large variety of creatures of all sorts, these are those races that have organized themselves into what those on the surface would consider civilized cities.  In fact, at one time Underdark was home to the single largest city in the work, known far and wide as Everdark.  However, the city was submerged under the waters of a great underground sea, it's vast cavern now known to those that dwell in Underdark simply as The Abyss.

The Cult of Voloid

Outside of known excursions into the affairs of The Drow, it is unknown what effect The God of the Void and his zealots had on the races, lands, and cities of the underground world. Unfortunately, their effect on The Drow was significant and they allied with several of the Drow houses in an attempt to establish itself with Ulteran, the main city of the dark elves. While they were successful, as soon as the God was defeated, they were banished and the reputation of the houses that helped them have suffered.

Major Settlements & Locations

The Abyss: Once the location of the largest settlement in the Underdark, this vast underground sea now dominates the Underdark.
Ostivalle: With the destruction of Everdark, Ostivalle is now the largest multi-racial city within Underdark.
Manitol Derith: The largest duergar city within Underdark.
Privels: The home of the Illithid with the dark confines of the lower world.
Iostol: The primary city of the Svirfneblin (Deep Gnomes).
Brul: Home to the free Derro of Underdark.
Wicos: A city with a large mix of races living within its walls. Outside of Ostivalle, Wicos has the largest population of humans, elves, and Shadar-Kai in the Underdark.
Siveran: A large Drow settlement in the Underdark, often considered to be in a fierce rivarly with Ulteran.
Ulteran: The largest and most powerful Drow city under the surface of Percens.
Clanhome: A small dwarven settlement that was once part of the Kingdom of Divmar.
Divmar: A large dwarven city that for many years was under the control of a Lich and overrun by undead. Recently freed from the Lich's tyranny, the city is in the process of trying to recover it's former glory.
Vilmar: Once the second largest city in the Kingdom of Divmar, it was forced to become it's own independent kingdom when Divmar was mysteriously cut off from the rest of the world when the Lich took over.
Ruins of Cestil: Once a powerful Drow city, it is rumored that a magical catastrophe is responsible for its destruction although no one knows for sure what caused the city to crumble almost overnight many centuries ago.
Ruins of Kronul: A former duergar settlement that is now rumored to have been taken over by a Death Tyrant.

by Spencer Doherty