Deities, more commonly referred to as gods, are beings of immense magical power who operate on a level far above most magicians and magical creatures. The Old Gods are the primordial entities that are responsible for the creation of the universe, magic, life and reality itself, as well as the 'parents' of the modern deities of mythology. Alice stated that to the modern gods of myth, humans are like toys, but to the Old Gods, they're like cells in a body.
While the gods of myth can take an active part in human lives and affairs, most choose not to. The "Old Gods" almost never interfere with human affairs as humans are seen as being so far beneath them, only warranting attention if humans prove "malignant" by doing something as extreme as killing a god. When Quentin Coldwater killed the Fillorian god Ember, the old gods cut off access to magic from all worlds. Leaving only those who were inherently magical (having magic in their DNA) like Deities, Demigods, travelers, Questing Creatures, Werewolves, Vampires, Bunnies and other magical creatures with any magical abilities. Hades stated that magic itself is a tool the gods use to keep humans in check. Taking it away when humans need to be punished or reminded of their place in the grand scheme but inevitably magic always comes back, even if it takes a millennium.
Deities come in many forms, as diverse as the humans who worship them and can generally be characterized by their extreme durability, intelligence, nigh-immortality, and advanced magical ability. The power and complexity of magic a deity can perform appear to be nearly limitless as Ember and Umber were capable of creating Fillory, a fantastical world filled with all manner of life and magic, and they were equally capable of destroying it on a whim. Even Umber, with no assistance, was capable of creating a pocket world of his own design. There are various kinds of gods and goddesses with different origins, though it can be inferred that their depictions in mythology are an embellishment of their true selves.
While the purpose of the gods has yet to be expanded upon, The goddess Iris told Julia that their work was "much more big picture" and the act of creating and destroying worlds was just a small part of what they do while they occasionally answered a prayer or two to help keep up morale. It has been stated that a gods power and potential is wasted if they focus all there time and effort on an individual world or species. Gods at least in the case of Julia a human turned goddess, can become more powerful through the act of answering prayers, performing miracles and granting favors or benefits, but most choose not to. This shows that gods become more powerful in actively using their powers for others or doing good deeds. This is based on Deities appearing to draw their power from something akin to a “Seed of Power” according to Persephone within themselves. This seed can grow in strength when doing the activities akin to being a god such as answering prayers or performing benevolent deeds. While gods' seed appears to not run out of magic, it can be depleted when a deity gave their entire being into a creation such as with Prometheus and Julia creating the Seven Keys.
Most gods have a megalomaniac view of themselves. Treating humans as though they are disposable and that any interaction they have with them should be considered a blessing, stating that the mere act of sharing their seed is to be revered as a gift. Although, due to their virtual immortality and great talent, is it not much of a surprise. There are some gods, however, who are at the very least ambivalent towards humans such as Iris and some even occasionally help humans like Persephone. Deities can also elevate certain lesser individuals to the level of a deity, granting them seeds of magic that can grow to the point that they become gods and join the pantheon, as seen with Julia Wicker, who was gifted a seed of magic taken from Reynard the Fox and grew its power within her. Elevating herself to a deity, "Our Lady Of The Tree".
Though not yet expanded upon, it would appear as though gods possess a physical form, as seen with Ember and Umber, that can be destroyed. Reynard the Fox, on the other hand, has shown the capability of possessing the body of another and work through them, while only briefly showing his true bestial self. Though he first appeared as solid matter, able to hold the severed heart of Richard Corrigan, his form was that of Persephone before he entered Richard's body.
It is shown that having the biological essence of a deity within you gives Magicians a lot more power than they can usually muster. This imbues Magicians with the power equivalent of a Master Magician, allowing them to touch objects of immense power, such as the enchanted Leo Blade and the key to the Wellspring, and cast spells of devastating magnitude. The effects of the boost wear off after an unspecified amount of time.
- Reynard the Fox - Pagan Trickster God
- Zeus - God of the Skies, King of the Olympians
- Hades - God of Underworld
- Persephone - Our Lady of Underground, Queen of the Underworld
- Bacchus - God of Wine and Revelry
- Prometheus - Titan, Creator of Man
- Iris - Messenger Goddess
- Julia Wicker - Our Lady of the Tree (formerly)
Demigods are the children of a deity and a human. Due to their heritage, they hold an incredible amount of magical power. Demigods who are unaware of their true status might use their innate abilities subconsciously, as seen when it was revealed that Senator John Gaines had been subconsciously influencing his political campaign. Everything that John tried to accomplish in his life, he succeeded. Penny stated that when he performed a Psychic probe of John, he had more magical energy coming off of him than every magician on Earth combined.
In the books, a human can become "3/4" of a god, such as a Nymph, nature spirits with incredible magical capabilities. Also, Quentin Coldwater was able to briefly utilize the power of Ember and Umber after slaying them, which allowed him to restore Fillory.