Order of the Six

The Order of the Six are six Archdemons (Hell Royalty]), lietenants to the Dark Lord].

Background
For all of eternity, Hell has been ruled by an ancient order of evil; six sovereign chapters of the six eldest demonst gods--descendents of the six unholy bloodlines born form the primordial black heart. These Archdemons rule over the six inner circles of hell (including Deathlands, Slough of Torment, and Spire City of Dis, built on the ruins of Babel).

Khan Maykr made a pact with the Order of the Six in order to be allowed to build factories in Hell to process Argent Energy, one of these was built in Nekravol, City of the Damned..

Of the Six only one is known Erebus, ruler of Spire City of Dis. Above the Six, rules the Dark Lord, the Nameless One.

Behind the scenes
Another of the Six, maybe Satan although this is not confirmed, and Satan might just be an idea out of Judeo/Christian mythology only, and not part of the true Hellscape.