Deities exist in this world and are real; their influence and affect on daily life is primarily exerted through the faithful. While it is not entirely without precedent, it is very rare for deities to ‘physically’ manifest in the world.
This list is not exhaustive and is not meant to be – the pantheons of all of the peoples of Greyhawk is too vast to track. Furthermore, deities have been updated and modified across iterations of Greyhawk materials. Consider this list as a starting point to help give you some insight into the setting and some direction in terms of your character’s faith, however deep or important that faith is depends upon you.
If you are looking for a deity and don’t see it or what you see does not align with your understanding or expectations – please let me know and we can potentially revise this list and these descriptions to better align with the storyline you create and this setting.
Human Deities:

For Elves, Dwarves, Halflings & Gnomes: refer to pantheons in PHB.