The realms beyond the elemental planes, with the exception of Hell itself, are entirely unknown. It is said the gods make their domains in these strange realms beyond the great fog of cosmological chaos that clouds the planes and drowns them in eternal darkness. Long ago there were some mentions of old planar travelers being able to vist these realms, but for whatever reason those exact places are now entirely unknown to the world, and some believe they simply do not exist. If the gods are real, that is where they lie, but until one discovers a way to locate one of their realms, it is entirely plausible that there are no realms beyond the elemental planes. With plnar travel being near impossible this day and age, its unlikely one would be able to find these realms.
The Void Realms
While the existence of god realms beyond the Elemental Planes is debated upon, the Realms even further than that are entirely theoretical. At least, that's what many shcolars whish was true. These so called Void Realms are places that do not exist, and yet are unfathomably and horrifyingly real. They are a plane of nothing, and yet some...thing exists there. It is theorized from scholars who soon go mad trying to comprehend the existence of this realm of blackest nothing that the strange eldritch beings emerge from this realm, from places outside the very fabric of space and time. Bound by absolutely no laws, they are a realm of most vivid nightmares, and a place where to even think of these realms for but a moment is to welcome a rapid descend into insanity and despair, for these are the realms that should never be visited, and we can only pray never leak into the Mortal Realm. However, with eldritch creatures becoming more frequent, many learned men fear that the leak ahs already occurred, and now the world is but a sinking ship with no way to plug the leak...