Fey - Fey are alien creatures from the astral sea who knew nothing of time or causality until the astral sea became entangled with the material plane. Their behavior is governed by arbitrary rules that they placed upon themselves in order to play a game of causality. It cannot be stressed just how arbitrary these rules are - fey have godlike powers and they have chosen their weaknesses themselves. The best guess of Aarnian scholars is that fey in fact willfully choose to enforce their own rules on themselves. For instance, a fey with a weakness to a cold iron blade blessed by a shoemaker on a Tuesday will not actually be harmed by the blade, but will only pretend to be. Those unlucky souls trapped in combat with a fey normally don't care about any such distinctions.
Fey can be killed, but even this appears to be an act. Some time later the slain fey will begin a new life in a new area, though fey don't seem to carry grudges between "lives." It is almost as if fey are playing a role in their game, and in fact their entire identity is a facade. Despite this, one can safely consider fey to be method actors. They will always follow their own rules, despite their seemingly chaotic and arbitrary behavior.
Doppelgangers - From the front, they appear to be normal human beings. When one views them from behind, they see the true horror of this fey. Doppelgangers have no back, and are completely hollow husks. They steal the bodies of others in order to feel more complete, and often take on the appearance of their intended victim before absorbing their body, in order to capture them more easily. Their most common form of attack is changing themselves into a semi-corporeal projection inside a mirror and leaping out at their victim after assuming his or her form. Another common method of attack is revealing themselves, already haven taken the form of their victim. They do this carefully so only the victim will see - and hopefully pursue the doppelganger into an alley where they can be slain in private. Once absorbing their victim, the body will slowly decay and deteriorate, forcing the doppelganger to abandon its host and find a new one. Such a body will appear normal from the front - but appear as a rotting corpse from the back.
Dryads - Dryads are fey who live very close to nature, often merging their souls with the souls of plants. While bound to the souls of plants, Dryads appear as lovely, serene, and seductive maidens that will often abduct men to either eat them or use them as sexual slaves. It is widely thought that killing a dryad's tree will kill the dryad, but this is in fact untrue. When they are unbound to a plant, dryads become screaming spirits of horror called yettiks who will mercilessly slay any and all creatures who are not native to their forest, regardless of their innocence. A yettik appears as a floating spectral werewolf with no hind legs.
Fairies - Fey of mischief that fill many roles in society. They only appear to those they want to see them, such as virginal maidens, drunken men, questing adventurers, or others of a specific type. Fairies delight in taking credit for natural processes, such as a sunrise or the leaves changing color in autumn, often leaving small jars of paint underneath a freshly changed tree. Other fairies will grant wishes as rewards - or as punishment. Still other fairies will lead people into trouble and tempt the mortal as a kind of game; if the mortal resists, the fairy will only try harder but will not directly interact with their toy. Despite their diminutive appearance and usually harmless nature, Fairies are actually the most powerful fey, and are only one step away from godhood.
Grassrunners - Often mistaken for elves, grassrunners appear to be human children wearing green or yellow, with long thin ears like a rabbit. They collectively chose their current form once man became the dominant force on the planet, and few, if any, know what form they used before. They enjoy playing panpipes, dancing through fields and enticing mortals to dance with them. Their revelry is so intense that any who join their celebration are found dead the next morning. If a grassrunner is encountered while not celebrating, he or she is usually watching a stream, and may provide the answers to ancient questions or impart essential wisdom if treated with respect. Those who treat a grassrunner rudely will have some tragedy befall them by the next sunset.
Ghouls - Often mistaken for undead, Ghouls are actually shapeshifting fey. Their true form is that of an emaciated, deformed corpse-like being with a maw of double-rowed teeth, similar to a shark. They will often take the form of animals to lure travelers off paths in order to eat them in privacy. They will also eat corpses, and often live in graveyards. They are quite physically powerful - but will only actually attack and kill those who step foot on its territory of sand, allowing wary travelers to pass unharmed.
Mothmen - Mothmen are fey that are portents of bad luck. They usually appear as 7 foot shadows with moth wings and large, yellow eyes. They are associated with malevolence and are often blamed for disaster, but they are actually curious creatures that bare humans no ill-will. They can sense when a preventable disaster caused by humans will claim much life in the near future. They simply gather to watch the chaos. Sometimes they will show themselves to humans as a kind of game; to see if the humans can realize the disaster is coming and prevent it. Most often, the humans are too frightened by the mothman's presence to actually put two and two together and stop the disaster.
Nuckelavee - A horrible fey who appears as an antlered male human torso atop a deer's body. They have only a single eye in their forehead that appears as if it is on fire. Perhaps the most distinguishing characteristic of nuckelavee is the fact that they have no skin; their veins, muscles, blood, tendons and sinew are all plainly visible. They are usually found near salt water and fresh water acts as a repellent to them. They will not willingly cross freshwater streams or rivers even with the aid of a bridge. They are the bane of coastal villages and farms; they can cause plague, famine, and will often kill domesticated creatures with impunity.
Nymph - Usually found near springs or ponds, Nymphs are similar to dryads, but instead bond their soul to a place instead of a living tree. If Dryads are considered lovely and seductive creatures, Nymphs are even worse - they are almost irresistible sexually, but have a faux-modesty about them that they use to confuse and manipulate. Tales say that seeing a Nymph disrobe can blind a man, but in actuality, Nymphs can cause all manner of afflictions to the human body. This can include blindness, deafness, causing their victim to become mute, become completely numb, paralyzed, or even dominate their mind completely. Nymphs enjoy nothing more than taking mentally dominated human slaves as servants.
Shadowling - Also known as shadow people, a shadowling is a fey that enjoys spying on humans. They cannot be seen if looked at directly, but can often appear as glimpses in peripheral vision. If they feel that they are being threated by exposure, they become malicious. They will start fires, cause accidents, or do anything to scare away, intimidate, or even kill the person who can see them. Young astralmancers are often tormented by shadowlings while their powers are developing.
Soul Twister - Large black shadows with long white hair, no legs, burning red eyes and a tattered cloak-like appearance, a soul twister is a "ghost" from the ancient time before undead creatures existed. A soul twister is ancient, primal, and vengeful. Trapped on Aarn when the astral plane was first bound to it, they hate all life and go out of their way to destroy it, scar it, mutilate it, and cause suffering. They are nourished by the fear, sorrow, hatred and anguish of corporeal creatures, and a single soul twister can turn a vibrant town or forest into a barren wasteland of black, thick cobweb-like tendrils overnight. Nothing brings them pleasure like bringing a mortal's worst nightmare to life, even if it takes years to set up and prepare the event. Perhaps the worst characteristic of the soul twister is its psychic ability to permanently scar the souls of those unfortunate enough to survive encounters with them. Madness, paranoia, and hallucinations are some of the more tame effects that survivors can suffer from for the rest of their lives.
Still Hunters - Fey that take on the appearance of inanimate objects, still hunters will kill indiscriminately, but remain completely motionless whenever observed. They often take the shapes of statues, dolls, or sometimes even weapons. Against a group they are nearly powerless and can be bound or sealed. Against a single person, however, and the still hunter will move whenever the unfortunate victim blinks or glances away. Still hunters are incredibly fast, and once within striking distance they can eviscerate even the most skilled hand-to-hand fighters in the blink of an eye. By far, still hunters are the most dangerous at night or in the dark, though it seems through some sense of fair play they choose not to attack during these times. This may simply be them wanting their prey to know what is coming, however.
Wendigo - A cannibalistic fey that possesses the bodies of those who during times of famine resort to eating the flesh of their own species. A possession by a wendigo is more subtle and nuanced than most other possessions; the original owner of the body remains intact and conscious, and for quite some time still feels like they could possibly be the one controlling their body. The wendigo is in reality controlling the body completely from day one, simply behaving as if the original soul were controlling it. Saying aloud what the person wishes to say. Doing, usually, what the person wants to do. Wendigos do not just feed on meat, they also feed on the horror, shame, and despair of those who, from their own experience, become hopelessly addicted to cannibalism.