Dark one

The dark ones were a race of humanoids native to the Shadowfell and often found in the Underdark. They were natural rogues with powers of stealth and shadow. They were apparently divided into two species or subspecies: the short, squat dark creepers and the human-sized dark stalkers.

"For our kind, there is nothing but the darkness."

- Dark Ones proverb.

Description
Although dark creepers and stalkers were different in height and build, they shared certain characteristics in common. Their eyes were disturbing slits of a uniform, dead grey color, reminiscent of some blind cave fish (both the iris and pupil were present, but of the same color). Their skin was cool to the touch. Their hair ranged in color from inky black to stark white. Dark ones moved gracefully and tended to be lightweight for their size. Their voices were soft, even when angered.

Although dark creepers and dark stalkers looked very different, all dark ones wore only black clothing. Cloaks, wraps, masks, turbans, and any other clothing that covered their faces was favored.

Personality
The dark ones hated light of any kind, and would assault any being who carried a source of illumination, whether a lantern, a torch, or magic. They did not harass those who passed without the aid of an artificial light source.

Abilities
Three times per a day, a dark one was able to envelop themselves in cloak of shadows, concealing them from view even in bright light. This darkness was magical, so a foe needed the ability to see in magical darkness to penetrate it.

Dark ones, unusually for their shadowy habitat, did not possess darkvision, but instead relied on their acute senses of smell and hearing as a form of blindsight.

However, when caught in daylight (natural or magical), a dark one was dazzled or badly demoralized in all ways.

Combat
Dark ones were craven creatures, but highly skilled in stealth and in ambush. They usually surprised and picked off their foes from the shadows. They were natural backstabbers, most dangerous when making a sneak attack from flanking or surprise. Dark ones fought in total darkness wherever possible, and beat a hasty retreat if they lost the upper hand.

Dark ones typically wielded daggers, though dark stalkers were also known to wield scimitars.

Society
Among the dark ones, the dark stalkers were the leaders. They led dark creepers in ambush and combat.

If not working alone, dark ones typically operated in bands of two to five dark creepers led by one dark stalker. Their tribes comprised less than a hundred members, with twenty to eighty dark creepers and two to five dark stalker leaders.

Language
Dark ones spoke their own tongue, called Dark One. They seemed to comprehend Undercommon, but did not speak it.

Dark ones did not speak so much as breathe words. Their native tongue sounded like a series of punctuated sighs, with subtle differences in tone changing the meaning.

Homelands
Besides inhabiting the Shadowfell, dark ones were largely to dwell in underground areas, such as the Underdark.

Relationships
The dark ones were an enigmatic people, even to other races in the Underdark. They usually only came into contact with outsiders when they stole some item from others or defended their lairs from their foes.

They often lived alongside shadar-kai or intelligent undead. They would serve these creatures agents, assassins, messengers, and spies. In the Shadowfell, they were often subjugated by death giants.

Despite, or perhaps because of, their overlapping environments, shadar-kai and dark ones had a violent hatred of each other. Among the dark ones, it seemed to stem from their natural isolationism as well as jealousy, but the shadar-kai seemed to hold a deeper grudge. Scholars suggested the grudge stemmed either from some knowledge the shadar-kai held of the future, a trait of the dark ones' own inscrutable connection to the Plane of Shadow, or perhaps that the misty history of the dark ones began with the mortal champions who once thwarted the shadow fey's attempts to merge the Material plane and the Plane of Shadow.

History
In the Year of Lightning Storms, 1374 DR, a group of dark one mercenaries (a dark stalker and four dark creepers) were hired by clerics of Shar involved in the operations at the Temple of Mystra in Wheloon and the Lost Refuge in the Vast Swamp in Cormyr. By early Eleint, they'd taken up residence in the Tomb of Chonis to watch over the petitioners traveling between the two points. In particular, they watched for groups investigating these petitioners. Adventurers investigating the Temple of Mystra may have encountered them.