The Elder Elementals

And lo, Gangrosh stood on the corner of the earth
And before him the ground rose up, like a living thing
Like the back of a cat arching.
It rose up and looked at him with eyes that were green like new growth on a pine.
And in a voice like an earthquake, the Elder said,
"Who is it that stands before me today?"
And Gangrosh answered it, "One who seeks guidance from the wisest of all beings, the Elder Elementals."

— Excerpt from "The Epic of Gangrosh," translated from the original Giant

Not quite gods, but neither truly mortal, the Elder Elementals are the manifestation of the elements in corporeal form. As the rulers (and some say creators) of the four regions of the Elemental Plane, the Elder Elementals are incredibly powerful beings whose very essence is embedded in the plane itself.
It is unknown exactly how many Elder Elementals exist - some, like the Leviathan and Behemoth, are well-known in myth and legend, while others are secretive, never revealing their true names to mortals. Sources suggest that there are at least two Elder Elementals for each of the four Elemental Planes, as well as certain Elder Elementals which embody less "pure" concepts of elements - such as Saumen Kar, the well-attested Elder Ice Elemental, which is not truly the element of water.
As beings that are the pure manifestations of the concepts of their element, Elder Elementals are without fixed form, and are immortal. It is unknown whether it is possible to kill an Elder Elemental - one school of thought argues that because the Elder Elementals are individuals, it is logical that they can be killed, like any other powerful being. However, others argue that because the Elder Elementals are tied in with the very concept of the element itself, they are impossible to truly kill so long as their element exists.
After the Great Arcane Cataclysm, the Elemental Plane was completely cut off from the Material Plane, and as a result of this, the Elder Elementals were also cut off. There have been a few journeys by mortals to reach the Elemental Plane and converse with the Elder Elementals since the Great Arcane Catacylsm, but these pilgrimages have been few and far between, and not many have returned to tell of their experiences.

Structure

The Elder Elementals are only loosely affiliated with each other, forming and discarding allegiances with each other regularly. Commonly allegiances are stronger between Elder Elementals of a given plane - for example, all of the attested Elder Air Elementals are closely allied with each other and often act in concert as the Council of Air
Usually, most of the elementals residing in a given plane offer their allegiance and obedience to one or more of the Elder Elementals of their plane. For example, the vast majority of the inhabitants of the Plane of Water are the subjects of the Leviathan, who makes the rules and governs them as their Prince.

Worship

The Elder Elementals, due to their immense power, have historically been worshiped in various fashions across multiple planes. Although not technically gods, many mortals see their indisputable power and immortality as functionally identical to those of gods, and see no reason not to worship them.
Worship of the Elder Elementals is often paired with a worship or reverence for various other elemental spirits, including elemental place spirits of the Material Plane. For example, a follower of the Leviathan is likely to also honor local water spirits, such as the spirit of a nearby lake or river, or the spirits of thunderstorms.

Type

Religious, Pantheon

Subsidiary Organizations

• Council of Air

Controlled Territories

• The Elemental Plane