For the most popular tabletop RPG in the world, it's not surprising that many third parties, both licensed and otherwise, release additional content for Dungeons & Dragons. Most supplimental materials make an attempt to fit into the world already designed by TSR/WotC, but are not necessarily canon with any official material.
The Ashmede function as Hell's police force. They act only on Asmodeus' word, and hunt down and execute any who are found guilty of breaking the law of the Abyss. They can attack within seconds by teleporting directly upon their prey, create an aura of fear at will, and cast magic that charms and kills as well as hacking away with their huge scythe.
Blood Maidens are unfortunate water nymphs who found their home sea poisoned by the blood of Kadum. After glutting themselve they found themselves addicted to blood, and their forms changed to suit their new source of food. They typically seduce individuals and then drain them while they are enspelled, but they will attack anything with blood when hungry.
The Darksphinx are the result of a challenge made, and won, by one of Hell's rulers of a powerful Sphinx. Because the Sphinx lost, she was forced to mate with a demon and create a race of half-sphinx half-devil. These Darksphinx are trained to act as bodyguards for Hell's nobility, although some suspect they are nothing more than a network of spies. They are adept at fighting with their claws and with specialized blades, but they also possess the prophetic ability of their less dark ancestors.
Enforcer of DisEdit
Dis is the most populated city of Hell, housing even a significant population of mortals. The Enforcers keep the peace through a combination of threats and the skill with a blade to back them up.
An unfortunate, though approrpriate, fate awaits those bards who sell their souls to demons of the Abyss. Kept as entertainers, the Grisly Minstrels are thoroughly evil creatures that play screaming lyres personally constructed out of the still living bones and vocal cords of mortal bards.
Hadriel, once just an erinyes, clawed her way up the social ladder to make her way into Mephestophiles' court. After the tragic death of her husband left all of his lands and wealth in her possession she put into motion plans to reach even higher. She could never face Mephestophiles on her own, and therefore she plotted to secure Asmodeus' favor. Her gift for such a boon would be an entire world. Disguising herself as a wealthy heiress, she created a woman's society which is in actuality a front for demonic runes spread across the entire world which, when completed, will drag the entire realm into the Abyss. In her natural form Hadriel can rend flesh with her long bony claws as well as cast powerful domination magic.
Kere are the footsoldiers of Baal, powerful and agile giants that are adept at fighting in any situation and any surface. Because of their spidery features Drow consider them abominations in the eyes of Lolth.
A former celestial, Naamah is directly responsible for most of the original celestials who fell. When she was finally found out she was cursed with her current apperance, but it did not make much difference to her. She still delights in being a thorn in the side of celestials and foiling their plans no matter what they might be.
Living embodyments of sickness, Plague Angels are often given as gifts to evil priests. Upon command they will secretly visit enemies and other troublesome mortals and strike their bodies with powerful contagions. They can disguise themselves as mortal races, but will return to their natural shadowy form in combat.
Skein are the remaining elf women who, centuries prior, plotted to overthrow the gorvernment of the city of Hedrad. When they were found out they were cursed with half-spider bodies and run out of the city. Nowadays they dwell in the surrounding swamps and capture and torture anyone unlucky enough to come close to their dwellings.
Sthein are half-naga half-humanoid hybrids. They possess shapeshifting magic that lets them take either form fully, but are rarely seen as they only concern themselves with the aquisition of knowledge.
The Striga are minions of Hadriel taken from the most loyal mortal members of her operation. After an extended, and very painful, transformation, the Striga lose all their normal senses but gain the ability to discern the true motives of anyone they "see". They rarely fight, but they can deliver poisoned blows from their claws.