Duergar

Duergar (pronounced: /ˈdjuːɜːrgɑːr/ DEW-ur-gar), also known as gray dwarves, are a subterranean subrace of dwarves. They carve an existence in the Underdark, often near volcanoes. Their kinship to other dwarven subraces could be compared to that of the drow to surface elves. Like their other dwarves, duergar were typically stocky figures, though beyond this there were many differences. Both male and female duergar were typically bald, with females also lacking the capacity to grow facial hair. Many were also thinner than their dwarven brethren. Most obvious, however, was their dull gray skin and hair, often matched with an equally stolid expression.[9]

Because many duergar found on the surface world were criminal exiles, a surface dweller who encountered one of the gray dwarves was likely to notice facial and arm tattoos that marked the duergar as a traitor to his or her people.[9]