Mortal Fay

The races born of the Fay Queen. Almost all fay are seriously injured by iron; direct contact with iron causes severe burns and renders the Fay incapable of producing glamours.  

The Kindred of the Courts

  Tuatha - *They are the Progenitor Fay, the first of mortal fairyfolk. I crafted them within the Faywild partly from its very matter, awakening clans of them throughout its expanse. They are ethereal half-beings whose bodies aren't always bothered with things like 'tangibility' or 'biological processes that follow the laws of physics.' (for reference for a Tuatha in its native form, check the sketch I tossed into the Art channel. They are half physical/more-or-less-organic matter and half threads of fay energy woven together into a malleable but generally humanoid form with a variable number of limbs)
*Outside of faywilds, they have a little trouble with, well, properly existing. They can manage it, but it's not very comfortable and they may flicker in and out of visibility or unravel with extra frequency. Furthermore, a non-fairy who perceives at a Tuath in its native form for too long will start to suffer from a migraine with aura, while a Tuath who is so perceived will also feel something equivalent to a migraine.
*To counteract this, whenever the first Tuatha clans begin probing the boundaries of the Faywild, I appear to them under a moonless, star-studded sky, and instruct them in how to craft ball-jointed exoskeletons out of a substance I will just now dub ceramitin (a play on ceramics and keratin/chitin/lignin), which has the look and texture of porcelain but without porcelain's nasty habit of shattering. Essentially, these Tuatha look like the Vizadri/maskbound of the older iteration of the world, down to the hidden mouths.
*These shells keep their bodies comfortably contained and the more organic parts solidly existent regardless of where they are, and sidestep all the problems of being perceived. With their glamour, Tuatha will often decorate their shells with swirling filigrees and vivid colors, like the embellishments on venetian masks (which their faces resemble, albeit with five eyes instead of two)

- without a ceramitin shell I guess they'd have a hefty negative Con modifier they were initially inspired by filibusterfrog's (of tumblr) fay worldbuilding in which fairies were the most beautiful supernatural creatures, but their beauty was kept in balance by their true forms being repulsively ugly and withered. But I thought it would be mean to deliberately make my first kids horribly ugly, and 'ugly' is a very objective term anyway, so instead they're cognitohazards
*Tuatha eat regular food to replenish the organic parts of their bodies; they reproduce when two willingly unwind fragments from themselves and then weave those two fragments together in a faywild sort of place, which allows the creation to come alive as a lil infant Tuath I also forgot those things
I was originally thinking of having the Tuatha be literal ancestors of the other fay kinds but it's now making more sense in my head if the humans who live within the Faywild when it forms become the ancestors of the other fay (ellyllon, nains, sluagh, etc) or like the ancestors of the ancestors of the other fay, I'm still thinking of how each fay kind gets to its set Court across the world

Peri -
Humanoid beings with four feathered wings and a spray of feathers at their temples. Their magic allows them to change the size of their wings at will - they can become large enough allow for flight and small enough to comfortably tuck away.

Ellyllon -
Abnormally gracile humanoids with large pointed ears. An iridescent sheen tints their skin.

Ferrishyn (singular Ferrish) -
Small humanoids with slightly childlike proportions, these people are typically 8 to 10 inches tall. Ferrishyn have semi-transluscent butterfly wings and antennae that mimic the shape of slower filaments. Capable of flight?

Nains -
Stocky humanoids who grow to roughly 3 to 5 feet tall. Every aspect of their appearance rings of the earth; their hair looks metallic, their skin like a boulder opal, their nails and teeth of quartz, and their eyes of wrought metal. They are not directly injured by iron like other Fay; however, direct contact with it does cause a sense of dread and discomfort.

Adhene -

Sluagh -

Merrow -
Vaguely serpentine merfolk with betta fish-esque frills. These people are amphibious, possessing both gills - which are found along their torsos - and lungs. Their frills can be held tightly against their sides, keeping them from being damaged when they slither around on land.

Changelings

Technically, all Fay are - or once were - Changelings. A more liminal space than firm racial group, Changelings fall into one of two categories: Young, mundane individuals who are shaped and changed by latent magic within the faywilds, or young Fay who find themselves stripped of their magic after living outside of the faywilds.

-Someone born a non-fairy who is raised from infancy to adulthood within a faywild, surrounded by the fay magic of their environment and the glamor of their caretakers, will over time absorb/internalize fay magic into their body. Their skeletal and muscular growth will slow, and be distorted by that magic, and eventually they will become able to utilize glamor, and in time be harmed by iron disrupting the fay magic in their bodies, becoming magically indistinguishable from any other fairy.
-Meanwhile, a fairy raised from infancy beyond the faywilds by non-fairy parents will have their natural magic dulled over time. As their natural magic fades, their body will internalize/absorb the shape of any glamors placed upon them at childhood (if they were disguised as a non-fairy species, for instance). Their growth rate will speed up over time, and their growth patterns will match the species of any glamor disguise placed upon them at infancy. In time, as they grow their body will cease being able to replenish their fading magic, and iron will no longer disrupt or harm them, becoming magically indistinguishable from a non-fay (although, if no glamor was placed upon them, they may resemble a fairy species in body)
The First
Those who did not choose to settle in a new realm and instead remain within the Faywild eventually settle into having digitigrade legs, with sort of Eohippus-like feet instead of straight up cloven hooves, antlers, somewhat bark-like skin, protruding vertebral spines, and tails. This occurs over the span of many hundreds of years; until then, like other Changelings, they tend to vary wildly in terms of appearance.