The Legacy of Fire
“But this was no mere superstition.
“The darkness at the center of the world is real, and its name is Rovagug, Worm from Beyond the Void and Harbinger of Apocalypse. He is the reason men fear the darkness as they descend into the earth. This primordial creature has calved countless horrors from his dripping flesh, and his foul presence seeps upward through the Darklands like a poison wind.
“Though he remains bound by the will of the gods, how long his prison—our world—can withstand his tireless thrashing, none can tell.”
—from The Chronicles of the Darklands
Imprisoned since the dawn of time, Rovagug seeks only to destroy creation and the gods. His increasingly restless stirrings are taken by many to be the cause of volcanic activity and earthquakes.
In the beginning, Rovagug sought to destroy Golarion. Already an ancient being even then, Rovagug was responsible for the destruction of countless worlds. When he turned his gaze upon a new world he was opposed by an unlikely collection of gods: Abadar, Apsu, Asmodeus, Calistria, Dahak, Desna, Dou-Bral, Erastil, Gozreh, Pharasma, Sarenrae, Torag, along with a number of other gods from more remote parts of the world. Many gods died in this battle, but their names have been forgotten; certainly the gods who sided with the Rough Beast will never be remembered. Unable, or perhaps unwilling, to destroy him, the goddess Sarenrae sliced open a hole in the Material Plane, and the archdevil Asmodeus bound him with a key only the Prince of Darkness could hold.
While Rovagug hates most deities equally, he reserves especial hatred for Sarenrae, who was instrumental in combating the Rough Beast long enough that the archdevil Asmodeus could imprison him. This hatred is returned by all other deities as well, and even feuding gods joined together to seal Rovagug away from the world. Rovagug is believed to have some relationship with the mysterious Groetus because of their mutual interest in destruction but he has no overt ties with the God of the End Times.