Two competing pantheons.
The Old Gods are the traditional sort each taking various portfolios. There are new Elemental Gods who have usurped some of the power of the Old Gods after a betrayal by one of the Old Gods allowed them to gain a foothold. One of the Old Gods was slain in the battle. There are also many powerful Demon Lords and Evil Gods. These are beings of lesser power that sit outside the official pantheons but who neverless attract followers.