Little is known of the Dark Tapestry—the darkness between the stars where inhabitants of Golarion believe true madness lies. The few beings able to survive in the vast, cold void of space are too alien for even the gods to comprehend, and present one of the greatest threats to the known universe should they wish to do so. Gods of the Dark Tapestry, known as the Elder Mythos, form two categories, in so far as such chaos might be categorized: the Outer Gods and the Great Old Ones. The Outer Gods are equivalent to true deities, whereas the Great Old Ones are less powerful: more akin to demigods, like the archdevils and demon lords. The Great Old Ones respect the Outer Gods and may be seen as heralds or high priests of their greater kind. For mortals, though, the differences between cults of gods of either category is practically meaningless.
The ancient, eldritch horrors of the Dark Tapestry are beings of immense power who—luckily—have thus shown little interest in Golarion.