Duergar
The Duergar are Gray Dwarves of the Underdark with a large city named Gracklestugh.
The party first met a Duergar named Hemeth in Sloodublop who was killed in the destruction. Later they met several in Gracklestugh including the solid Errde Blackskull, the slippery Lorthio, and the unfortunate Werz Saltbaron.