The Dweller Beneath is a monstrous eldritch entity, an alien intelligence with an insane plan which is to consume all life, not only in the cosmos but throughout the Megaverse, both physically and pyschically. It estimates that his plan will take another million years to achieve his goal, but he is patient. It's because of this plan that it orchestrated the successful uprising of one of the Splugorth's minion races, the Kreeghor, whom have unknowingly been serving the entity ever since.
The warrior race has carved for itself a totalitarian intergalactic empire in the "Three Galaxies", the Trans-Galactic Empire (TGE). Only one individual in the empire knows the dark truth, the Kreeghor Emperor. When its time to pass control of the empire to his successor, the chosen Kreeghor is brought to the Dweller Beneath before he assumes the throne. Where he learns the terrible truth and it bestows a tiny fraction of its power on him. The Dweller Beneath feeds on the psychic suffering of the trillions under the boot of the TGE.
The Dweller Beneath
The Dweller Beneath is an incredibly ancient entity, one that has been around for a million years. A skyscraper-tall pillar of moldy flesh topped with a gigantic cyclopean eye and greenish hair like growth in the upper part. It's a psychic empire which feeds on the suffering of sentient lifeforms.
Which has vast magical and psionic powers, including being able to telepathically communicate up to galactic distances. It is able to regenerate and can survive a 19 megaton nuke, though with grievous wounds. The entity can send out fragments of its essence which have the ability to take any form and maintain telepathic communication with the core. Each of which is extremely durable, able to take up to x8 as much damage as late 20th century main battle tank. The Dweller Beneath itself can shapeshift into any form up to 2 stories in height. It's able to bestow an insignificant sliver of its power on a minion who becomes the Kreeghor Emperor, giving him super powers, including the ability to survive a 280 kiloton nuke.