Ao

Ao is the Overgod. He was the one who created Selune and Shar who, in turn created Chauntea and Abeir-Toril. All gods answer to him, even foreign gods like the Mulhorandi pantheon as he controls the Tablets of Fate. Ao is the only being that can grant a divine rank higher than demigod.

Ao desires no worshippers and grants no spells to those that do worship him. He has, in fact recently been slowly editing anything that mentions him, including the memories of creatures, becoming more and more reclusive for some reason.

Behind the Scenes
Ao has been mentioned in several adventure modules to answer to a power even higher than himself (namely, the Dungeon Master).