Lords of Dust
The Lords of Dust are the powerful ur-fiends of the Dungeons & Dragons setting of Eberron who rule over all fiendish creatures. They are roughly comparable to the Demon Princes and Archdevils of the Great Wheel, except theye have largely all been imprisoned in various places in Eberron's version of the Underdark. They maintain vast cults that have secretly been working for tens of thousands of years to free them from their prisons.