In the Fourth Edition Monster Manual, Tharizdun is described as creating the Abyss and the demons that live there by corrupting a portion of the elemental chaos using a shard of pure evil. For this, all the other gods (good, unaligned and evil alike) banded together to seal him away. Fourth Edition’s Dungeon Master’s Guide states that Tharizdun is not mentioned by name in the Player’s Handbook or in the Monster Manual due to the fact that his existence is not widely known to mortals. Those who do know of Tharizdun refer to him euphemistically as the Chained God. Most of Tharizdun’s followers are elementals or have ties to elementals, and refer to him as the Elder Elemental Eye. The majority of the Elder Elemental Eye’s cultists (including Tharizdun’s exarchs) don’t even know he is a god, thinking him instead to be a powerful primordial. The 4th edition Tharizdun is not associated with aberrations, and the location of his prison is not known.
In the Dungeons and Dragons Novel Series “Abyssal Plague” Tharizdun’s prison is revealed to be a universe that has long since been destroyed by that realm’s own version of the Abyss known as the VoidHarrow. Mildly intelligent and with the ability to corrupt and warp living creatures the voidharrow spent eternity alone in this realm of utter destruction until Tharizdun was imprisoned there by the other gods for his creation of the abyss. The reason behind this realm as the prison in which he would be trapped was to leave him in a realm just like the one he would have turned the multiverse into if he had been able to, with all of his power intact he would have nothing to destroy and an infinite amount of time to lay out an infinite number of plans to free himself only for him to have no way of implementing any of them.