Lord Ao (pronounced: /ˈeɪoʊ/ AY-oh) was the Overgod of the worlds of Abeir-Toril and the Realmsian embodiment of The Balance, showing no aspects of any extremes. As Overgod, all deities and primordials of Abeir and Toril, even those who also operated in other spheres and planes, such as Lolth and Tyr, were subject to him. To be more precise, only aspects of gods directly connected with Abeir-Toril were under the power of the Hidden One.

If it were not for Ao's involvement in the Time of Troubles, he would likely have remained unknown to the mortals of Faerûn.

https://forgottenrealms.fandom.com/wiki/Ao