The Elemental is a well known and well established unit in the gaming universe, and they are invariably humanoid shaped hulks or amorphous blobs of the element they are composed of. This is lacking in imagination.

Spellseekers are strange creatures from the Astral plane that are drawn to the material plane by shoddy spellcasting or uncontrolled magic. They are vermin

Also known as Ghost Wasps

Beware, beware, the hidden snare.

Where the shadows linger, and fiends do fare.

Go on, run, hide and pray.

For the elder crow feasts,

on our souls' decay.

Strange creatures, half dreamed half imagined, figments of delerium, wisps of insanity.

'Do you feel it?'

'Feel what?'

'Feel... well, never mind, I'm just not feeling well'

So you want to rub a lamp, do you? Here are many mighty Genies, beings of great magic who might turn out to be your greatest boon or your greatest bane.

"A little bit of the arcane, hidden within the mundane."

-Victroinox, Archmage of the Circle of Masters

"I saw him! The Sorcerer! His skin cracked and glowed like it was smoldering beneath. His eyes burned like Sol and Radia. He spoke with a voice like a legion of hellspawn, in a strange tongue that parted the skies and reigned fire down upon the earth."

-Excerpt from Mycenae's Dissertation on Sorcerers.

How much hatred does it take to buy revenge?

The Red-Wind Rag; Trappings of a Bloody Death; A Malevolent Sheet of Scarlet and Ichor.

The poor boy.. Man, I mean. I tend to forget his age, given his appearance...

When a mission becomes something more.

have made thee as no other. All the treasures of the earth shall lie between thy eyes. Thou shalt cast thy enemies between thy hooves, but thou shalt carry my friends upon they back. Thy saddle shall be the seat of prayers to me. And thou fly without any wings, and conquer without any sword.
The Koran

The leftover remnants of Mind can sometimes cling to existence when the Body fails and the Spirit departs...

You see a glowing figure, four feel tall, it looks like it has been waiting for you. Suddenly, it flies right through you, and it looks like its coming around for another pass...

Behold, the Harbinger of ill-tidings, the blizzard rider, the thief of winter, the Stamagast.

Gentlemen, BEHOLD! The celestial spider!

It is the tortured and imperfect souls who most often cannot find a clear path to the afterlife. Weighted down by sins unforgiven, sins for whose forgiveness they never ask, sins they never regretted.
To be added to Remaking Undead when finished

Too many are the spirits of the Spirit World, these are only a few better known types.