Svirfneblin (plural Svirfnebli) first appear in D2 - Shrine of the Kuo-Toa. Although the name appears reminiscent of old norse, it does not appear in any ancient texts or folklore, and is almost certainly an invention of Gygax. Possibly inspired from svart- ('dark', 'black') + nibelung (a name for a type of dwarf found in Wagner's The Ring of the Nibelung)