Duergar

Duergar (pronounced: /ˈdjuːɜːrgɑːr/ DEW-ur-gar), also known as gray dwarves, are a subterranean subrace of dwarves. They carved out an existence in the Underdark, often near volcanoes. Their kinship to other dwarven subraces can be compared to that of the drow to surface elves.