The Elder Gods
Long ago, it is said that the Earth was the plaything of alien, godlike beings known as the Elder Gods or the Great Old Ones. These beings inhabited one of the Far Realms, extra-dimensional spaces which surround our own universe and interconnect to the Earth through powerful arcane portals. These entities were utterly alien in their motivations and desires to the mind of men, but they offered great power to those foolish enough to offer them worship, usually in the form of blood sacrifice. It is known that the barbaric Atlanteans were particularly dedicated to the foul worship of the Elder Gods in the Pre-Cataclysmic Age. The coming of the Cataclysm wiped away most of the knowledge of these beings, but it is said they still sleep far beyond the Earth in the Far Realms. One day they shall awake and turn their eyes upon the world of men once more. Then all the kingdoms of the Earth will tremble.
The most powerful of the Great Old Ones were named Nyarlathotep, Shub-Niggaruth and Yog-Sothoth. They were served by lesser entities, some of whom were already present on the Earth where they hibernated, awaiting the time of Awakening. Some of these Earthbound Elder Gods were known as Cthugha, Cthulhu, Dagon, Mordiggian and Ithaqua. Dagon, in particular, was worshiped in the lands of Zamora, Shem and the Black Kingdoms as a god who controlled the weather and could offer his worshipers protection from natural disasters and ill fortune in return for their obedience and human sacrifice.