D&D General Are creatures of the Ethereal Plane the Elemental creature type?

[Marandahir]

In my game, elemental energy is harvested to power magitech engines, mined as "Elemental Ether" from Ethereal Plane border crossings (with renaissance clockwork diving suits and chain lines to keep the miners from being lost in the ethereal mists, or worse, somehow end up in the Feywild or a Domain of Dread. To the "logic" of the setting, the "Ether" is the the intermediary substance between pure energy and chaos and the building blocks of reality "the Material". The Inner Planes are areas of the Primordial Chaos that are particularly refined and focused on a specific elemental, but Ether is what you get when you mix them all up, and part of what Elementals like Myrmidons, Genies, Giants, etc do is refine that ether into the material resources needed to build their fiefdoms. Demons and Dragons and their like are elementals that don't "put in the work" and instead are stealing the energy for their own domains and forces.

In that regards, the Humanoids who recently developed Ether Extraction technologies have a real moral risk of Dragon-Sickness if they don't sustain their resources. Overmining an Ether deposit could very realistically cause a localized Defiling Magic event. So the pull-and-tug of the setting is sort of a "what if Athas doesn't HAVE to end up with a Dark Sun?" – sort of exploring a world that could teeter in either direction.

In contrast, ghosts and other Incorporeal / ectoplasmic undead are lingering emotions that have gotten tied up with manifestations of the ether that are a bit like an immune system response – a ghost wall of sorts sealing off localized defiled magic zones and turning them instead into stabilized Shadowfell and Feywild crossings once their lingering regrets are resolved.

Finally, the Primal Spirits are specifically residents of the Ethereal Plane, while overseeing the Prime Material directly. While they share some narrative overlap with both Archfey and Dark Lords, their charge is also specifically tied to Preservation Magic, the healing of the world. Though these "natural gods" could also get consumed by hate and turn into demons a la Mononoke-Hime.

 

[Yaarel]

For me, an important characteristic of the ethereal is just how empty it is.

Several posts mention this about the Ethereal Plane. It is true the Deep Ether is an emptyish transitory plane. But the Border Ether is full of creatures and places. It is a part of the Material Plane and a mode of moving thru it and sometimes interacting with it.

That spirits and spiritual influences can roam invisibly within the material world is how the Border Ether can relate to animism.

It’s just vast grey expanse where ghosts cling to the edges of the real world and go insane, and the Radiant Citadel can be hidden away without the chance of something accidentally stumbling across it. Which makes it different to the Astral, which is full of colour and spirit.

I tend to describe Shadowfell as gloomy and colorless, Feywild as vivid and bright, and the Ether as pale pastels. (I explain the haziness of the Border Ether as gravitational force being partially visible.) I describe the Astral Sea like the D&D pictures, resembling Hubble Telescope images of outerspace: rainbow starry swirling within the darkness.

 

[Paul Farquhar]

But the Border Ether is full of creatures and places.

I see nothing in Gygaxian writings to suggest the boarder ethereal contains anything other than the occasional trapped ghost, transiting wizards and phasing spiders. It doesn't have "places" as such, only shadows of what exists on the prime material, and no native spirit inhabitants. And it's all grey. As I said, there is a case for reworking it in your home game, but the official version has never been a home for animistic spirits. They are very much Astral (or Feywild) types in D&D lore.