Dark dwarves, also called duergar or underdwarves, were a type of Mortalkind most often found in the Underdark of Somnum, far beneath the surface where light rarely reached. Related to Dwarfs and Derro, they stood around four to four and a half feet tall, with wiry but durable builds that usually weighed between 120 and 160 pounds. Compared to their dwarven cousins, they were leaner and less broad, their bodies adapted more for endurance and survival than raw strength. Their skin was typically ashen gray or dull stone tones, their hair stark white or pale gray, and their eyes washed-out shades that reflected the dim conditions of their homes. Their harsh appearance and smaller stature distinguished them clearly from other dwarves, as did their tendency to carry themselves with an edge of caution or severity born from life underground.
Dark dwarves were suspicious, disciplined, and often grim. The relationship between them and other dwarves was defined by a long and bitter history. Many tales claimed that they were once part of the greater dwarven people, driven into the depths during ancient wars and left to suffer in the dark. There, they endured enslavement, Curses, and constant struggle, which shaped them into a hardened and distrustful folk. This legacy fostered deep resentment toward their surface kin, whom they often accused of abandonment. Hill and mountain dwarves in turn saw dark dwarves as corrupted by their time underground, tainted by cruelty and dealings with dark powers. Though both sides shared blood and ancient traditions, these shared roots did little to bridge the divide. Instead, their history became one of rivalry and mistrust, reinforced by centuries of conflict over mines, stone halls, and the pride of which branch of the dwarves carried the true legacy of their people.