Why does Rebo need a post in the directory about this stuff of all places? Because they're different enough from a lot of the standards that having a reference is useful, of course! A few general facts, first of all. Being undead is bad. Regardless of the type of undead someone becomes, it's going to be negative in some capacity. In many undead the soul is imprisoned in the body while a malign undead spirit pulls the strings of the corpse. Some undead are imprisoned and actively tormented by the spirit while others are simply trapped. Other undead have the original soul in charge of the animating spirit, but the soul is horribly twisted into something dark and wretched. Perhaps worst of all, some undead spirits will devour the host soul and become a dark parody of it. Finally, some undead have their soul removed from their body and control the corpse from a distance, however the process often leaves them scarred and cruel. Thus, in the broad sense, undead can be classified as trapped, tortured, twisted, eaten, or stuffed in a box.
The simplest undead, basic skeletons and zombies, trap the living soul but are otherwise mindless automatons. The undead spirit has no access to the living soul's personality or memories. Making even these basic servants is kind of a jerkish thing to do since it pulls the soul of the dead from their rightful rest.
Ghouls are based on the Arabic creatures of the same name. Rather than being purple zombies that paralyze folks for some reason, they take the form of hyena headed, rotted humanoid with an open abdominal cavity lined with teeth. Ghouls can assume a hyena form naturally, as well as the form of any creature they have eaten. Some ghouls will only feed on dead meat and are likely to be friendly if offered cured or fermented meats. Other ghouls are wicked monsters that take on the shape of a humanoid to lure the living to their deaths so they can devour their entrails. People killed and eaten by a ghoul will rise as a ghoul themselves the next midnight. Ghouls can access the memories of their host soul, though they may not torture them depending on the disposition of the ghoul. Typically ghouls made from malevolent people will result in malevolent ghouls.
Ghasts are based on the Scandinavian creature of the same name. Ghasts aren't in any way related to ghouls, aside from their habit of feasting on flesh, living or dead. Ghasts appear as skeletons with long sickle-like claws and transparent, ghostly flesh. They exude a sickening aura of disease and filth. Contact or even proximity with a ghast can infect the living with ghast rot, a terrible magical malady that will cause anyone who dies while infected to rise as a ghast themselves. Ghasts trap the soul of their host, though they're unable to access the soul's memories. Particularly evil, vile people slain by ghast-rot will often rise as morghs, ghasts who possess prehensile entrails that end in lamprey-like mouths.
Bodaks are based on the Scottish bodach glas, the dark grey man, who is an evil omen of death. Bodaks are hairless humanoids with smooth, sooty grey skin. Their mouths are open in a constant, silent scream and have consumed everything from the bride of the nose down in a vile black abyss. In like fashion, their eyes are nothing more than empty sockets filled with darkness. Bodaks can rise spontaneously from people who die as a result of crushing despair. A living person meeting the gaze of a bodak will steadily drain their life away, hollowing out their soul and causing them to transform into a new bodak over the next twenty four hours. While a bodak's original soul is in control of their body, they exist in a state of despair and horror that can be lessened momentarily by visiting their awful fate upon others. Bodaks burn in the presence of sunlight. They have fleeting memories of their past lives, memories that flash and spark when they feed, leading many bodaks to believe that if they devour enough life energy they may return to life themselves. In reality a far more vile fate awaits them. Bodaks that consume sufficient life energy will undergo a horrible metamorphosis into a devourer, an undead giant that consumes its own host soul and hungers for the souls of others.
Ruddy or feral vampires are based on the English revenant, as well as some forms of the traditional Slavic vampire folklore. They are a corpse, though without decay and bloated with blood. This often gives them a reddish or purplish pallor. Revenants drain blood, spread death, and keep people up at night with constant shouting because they're jerks. Sometimes revenants will spread general mischief and misfortune while other times a revenant will doggedly stalk someone who wronged them in life. These undead trap the soul, though they have only vague memories of life. A person blood-drained to death by a ruddy vampire will rise as one themselves after three days.
Pale vampires are based on the vampire novels and stories that were created starting in the 1800s with a sprinkling of Slavic myth. These are the 'classic' vampires. Pale creatures with a predatory attractiveness to them. They have all the abilities one would typically associate with vampires, though feeding on blood isn't strictly required for their existence. A vampire that doesn't feed will become steadily more hideous in appearance in a very Nosferatu sort of way. When a vampire first forms they are little more than a predatory shadow. As they drain blood they gradually form into a bloody ooze that can, if it survives for forty days, transform into a full vampire. Vampires trap the host soul and have full access to its memories, often torturing the soul in the process.
Glamorous vampires (glampires!) are based on the baobhan sith (baivanshee) of Scotland. They appear as supernaturally attractive humanoids often dressed in green or white attire. They entice the living to secluded areas before attacking them with their blood-draining talons. Baivanshee are capable of weaving powerful illusions to beguil the mind and deceive the senses. While they are weakened by sunlight, these undead aren't actually harmed by it. Living creatures slain by a glampire's blood drain rise as a new glampire in their sire's control three days later. Baivanshee trap the host soul and have full access to its memories, often torturing the soul in the process.
Vulkodlaks are based on a wide combination of folklore that identifies undead werewolves as a sort of vampire, drawing from Greek, German, Serbian, and Armenian lore with a little bit of Japanese nukekubi and D&D vargouille thrown in. When a vulkodlak is first sired it appears fully human during the day and may not even be aware of its state. When the vulkodlak sleeps its ears sprout into bat-like wings and the head detaches to fly about and drain life from the living with its vile kiss, locks and doors springing open at its approach. In head form the undead spirit controls the vulkodlak while the soul remains in the sleeping body. As the vulkodlak feeds on more life energy it begins to change even while awake. First its ear-wings become permanent additions, then its hair becomes thick like a wolf's fur, then it grows hooked tendrils from its scalp, then its face becomes like that of a werewolf, then its eyes and mouth begin seeping sickly green glowing vapor, then its countenance becomes markedly infernal with horrible teeth and a long hooked tendril for a tongue, finally its head doubles in size and becomes a fully mature vulkodlak. Should a mature vulkodlak re-attach to its body, the body will undergo a horrible metamorphosis, becoming a hulking werewolf-like creature with massive bat-wings, a hooked tendril for a tail, and a huge toothed eye embedded in its sternum. The undead spirit is in control of the body at all times in such an abomination, slaving the body's soul even when the head is detached.
Vulkodlaks drain life force by biting or kissing their prey and a creature slain by this effect will become a new vulkodlak in a matter of seconds. A creature merely kissed and left alive risks becoming a new vulkodlak at the next sunset unless the vile affliction is cured. The horrifying howl of the vulkodlak paralyzes those who hear it with fear and the wounds they inflict will not heal magically or naturally unless their curse is removed. A mature vulkodlak can return to human shape, though they are betrayed by the wolf-like pads on their hands and feet. Vulkodlaks regenerate at a frightening rate and provided either half of a vulkodlak survives (head or body) it can regrow the missing portion by resting undisturbed for a full twenty four hours. If a vulkodlak's head is destroyed there's a small chance that the original soul will be able to seize control of its body again.
Penanggalans or krasue are based on the undead creature form south east asia of the same name. They appear as little more than a floating head trailing a massive tentacle that was once their digestive tract in addition to a nest of smaller tendrils, surrounded by a flight of will-o-wisps. Penaggalans can drain blood through their long tongue and creatures slain by a penaggalan's blood drain will rise as penaggalan themselves the next night under their sire's control. Penaggalans can reattach to their original body and walk around in daylight to pose as a normal, living person, the only mark suggesting their true nature being the ring of torn flesh at the base of their neck and a smell like vinegar. Contact with a penaggalan carries a risk of contracting a horrible supernatural withering disease. A penaggalan can cause inanimate objects to become misty and incorporeal, allowing it to pass through them. Sunlight destroys a krasue if they aren't attached to their body, so destroying or moving their body is a sure fire way to get rid of them. The krasue head itself is hideously resistant to all forms of harm save for flames. Penaggalans trap the host soul and have full access to its memories, often torturing the soul in the process.
Drekavac are based on the Slavic undead of the same name. They have a human-like torso, though they have legs akin to a kangaroo, a fox-like head, they have forearms like a raven's feet, and a tail like a raven's. Their whole body is covered in oozing sores, the sure mark of drekavac pox. These pitiable creatures are unaware that they're undead and believe themselves to still be children suffering from disease. Purely nocturnal, these monsters shroud themselves in rags to hide their shape and lure people to them with their child-like voices. They will attempt to get aid from adults or entice other children to play with them, actions that are likely to pass on lethal sickness to their victims. Their horrifying nocturnal screams can likewise cause illness in anyone caught in the blast of diseased breath. A drekavac's host soul is still in control, though they're locked in a child-like mindset and desperately seek out help and companionship, unknowingly passing on their affliction in the process. For reasons unknown, a drekavac is unable to infect its own parents. A child slain by a drekavac's disease will rise as a new drekavac mere seconds after death.
Draugr are based on the Scandinavian undead of the same name. Their appearance depends largely on the nature of how their remains were disposed of (burned, drowned, buried), though they all tend to have horribly blackened flesh as though from necrosis. Draugr are undead of significant magical power. They can massively increase their own size and weight, they can swim through earth and stone as if it were water, they can magically disguise themselves as a living person, they can wield lightning, fire, or cold depending on their nature, and finally they are all but impervious to metal weapons. Injury from a draugr inflicts the injured creature with devouring lightning, fire, or cold that consumes their flesh and feeds the draugr. If a creature perishes while under this effect they will rise as a draugr themselves on the next midnight. Draugr trap the host soul and have full access to its memories, often torturing the soul in the process.
Dullahan are based on the Irish creatures of the same name. They appear to be humans in general shape, often clothed in black riding gear or armor. Their flesh is the consistency of moldy cheese and oddly enough their odor is none too different. The most striking feature is the fact that they're headless, carrying their own skull as a lantern with sockets filled with hellish light. They also carry with them a staff of human vertebra that can double as a lethal whip that can easily sheer through flesh and bone. Dullahan typically wander the wastes of the Gloom collecting souls to carry to the Empyrean Spheres, whether those souls be free or trapped within undead bodies. As a result, all but the most powerful undead fear these wandering apparitions. Dullahan are known to wander Midgard on moonless nights in search of souls to harvest, whether from the living or undead. A person beheaded by a dullahan will rise as one themselves on the next new moon. The host soul of the dullihan remains in control of its body and is compelled to serve as a guide to the departed, however it is eternally resentful that there are none to ever guide it to its proper rest.
Wights are based on the Chinese Jiangshi and the German Nachzehrer. Wights vary widely in their appearance, though usually they are recognizable as who they were in death. Many wights have a shriveled, mummified look to them with ashen grey skin, however they may be skeletal, rotten, water logged, fossilized, caked with salt, stiff with rigor mortis, or even burning with the embers of their funeral pyre. Being wounded by a wight drains away the life force of the victim and should the victim die under such an effect they will rise as a new wight under their sire's control in a matter of seconds. The host soul of the wight remains in control of the body, though they are twisted with wrath, hate, and hunger. Wights have an insatiable hunger for the energy of the living and no small hope that feeding on enough living creatures may one day restore them to life.
Nightshades are just awful. Beings of gloom, shadow, and primordial chaos, nightshades are near the top of the list of horrible undead creatures you don't want to encounter. They aren't a single race, but rather a class of undead. Nightcrawlers are massive worms, nightwalkers undead giants, nightwings awful bat-like things, nightmæres horrifying horse-like creatures, nightfins giant amalgamations of all the worst sea life, nightgaunts grotesque gargoyle-like begins, nightdrakes truly apocalyptic undead dragons, and finally nighterrors are unspeakable amorphous masses of gloom that consume all they touch. Nightshades can create lesser spawn of both living and undead creatures by draining away their awareness, though only the living can be struck down by a nightshade's Finger of Death and rise as a new, true nightshade. Nightshade minions enslave the soul much as vampires do, however true nightshades completely devour it, becoming a twisted mockery of the personality they stole. Attempting to resurrect the person a nightshade once was will result in a nightshade's soul within a living body, a living body that will begin to decay at the undead soul's malignant touch.
Mummies, liches, and deathknights are all boxed undead stores in jars, boxes, and weapons respectively. Wraiths and ghosts are twisted, disembodied souls. The ghost is trapped haunting a single location while the wraith is free to roam and cause trouble. Shadows, phantoms, and specters are all incorporeal undead formed from both body AND soul. They all trap the soul of the living, though have no access to their memories. Shadows are exactly what they sound like. Specters appear as they did at the time of their death, though translucent and misty. Phantoms bear an amusing resemblance to the childish 'sheet ghost', though being smothered to death by one is far less amusing.
Some of this information is useful for non-spooky ponies, but we'll record it all here for the sake of convenience. Team Nightmære consists of a bunch of unliving nightmære shadelings, spawn, and one actual nightmære. Unliving creatures count as both living and undead, applying whichever state would be more beneficial to them regarding a given effect. When an undead creature is 'redeemed' they are transformed into a new shadeling (or nightmære spawn if they're strong enough), which is a rather profound experience.
By the kindness of their Mistress, they have been given another chance at life. A string of understanding washes through their mind. There is a single iron-clad rule that should never be broken. A rule that is burned into their mind.
Never make spawn of living beings.
Redeem the undead, for they are your fellow little ponies, even if they don't know it yet.
Be kind. Do better. Be faithful. Be loyal. Live with joy. Laugh and smile for the promise of new life. Act uprightly. Trot with integrity. Give of yourself with charity. Be gracious. Love without partiality. Be a friend to all. And most of all? Be the best you that you can be.
Creatures so created are not slaved to Sunder in the fashion of undead, but rather feel an innate sense of duty and loyalty to she and her cause of redeeming undead. Members of Team Nightmære generally don't hate undead, but rather they love and pity them, wishing to redeem them into more little ponies for the sake of friendship. Understandably, many sapient undead find this prospect horrifying.
All children of Sunder produce an aura of wuji, negative and positive energy in harmony, that erases fatigue both mental and physical in the living and quiets the hunger for life in the undead. They can focus this aura into a bolt of dawn that can disrupt, damage, and disorient both the living and the undead. Spawn can manifest far more powerful explosive blasts of dawn in addition to having expanded magical and martial prowess based on the abilities they once had as both a living and undead creature. This is in addition to the magic they possess based on their new equestrian tribe.
Arion (earth ponies) are between 4'6" and 5'6" tall and weigh around 400 pounds. They are stout and strong, with broad heavy hooves and a powerfully built body. In terms of general shape they could be compared to a draft horse. Basic arion magic involves having a degree of TK control over their mane and tail and producing TK discharges through their body to enhance strength and impact power. Arion talent magic is Empathic in nature (animal empathy, healing empathy, emotional empathy, plant empathy, artifact empathy).
Pegasus (sky ponies) are between 3'6" and 4' tall and weight around 200 pounds. They're light and agile, with hooves reminiscent of a bird talon and wiry, muscular bodies. Their wings are large and feathered like a bird's. Additionally, they possess a fan of tail feathers in place of tail hair as well as feathered breasts and fetlocks. Basic pegasus magic involves TK flight (creating and absorbing accelerations on one's self) and the ability to interact with clouds as if they were solid objects for the purpose of manipulating weather. More martially focused pegasi can hone their TK around their wings, lending them a razor sharp edge. Pegasus talent magic is Weather based (lightning magic, air pressure, gas magic, cloud magic, water magic, ice magic.)
Qilin (crystal ponies) are between 4'6" and 5'6" tall and weigh around 500 pounds. They're heavy and durable, with cow-like hooves, dragon-like tails, lion-like manes, and crystal scales on their lower legs, backs, and faces. Their tail possess in a ridge of fur and a poof at the end which obscures a heavy club of thick, stony scales. Basic arion magic involves using TK to harden their body, root themselves to the earth, and extend their senses into the recent future or past future. Qilin talent magic is Mystical in nature (divination, crystal growth, earth moving, stone shaping, time, the passage of seasons).
Thestrals (bat ponies) are between 3'5" and 4' tall and weigh about 200 pounds. They're light and agile with a thick, fuzzy coat, large ears, and three-toed hooves that possess surprising dexterity. Their wings are bat-like with a membrane that runs down their flank to their tail. Thestrals are able to map their surroundings with sonar, their calls falling above the range of most creatures' sense of hearing. Basic thestral magic involves TK flight (creating and absorbing accelerations on one's self), spider-climbing, and obscuring one's self with darkness (both audibly and visibly). Thestral talent magic is Darkness based (solid shadows, darkness creation, shadow teleportation, superior stealth, sonics).
Unicorns (star ponies) are between 3'5" and 4' tall and weigh about 200 pounds. They're graceful and leggy with a single fluted horn, delicate cloven hooves, and lion-like tails. They're built much more like a deer than a horse. Stallions often possess a beard. Basic unicorn magic involves TK manipulation of objects and light production. Unicorn talent magic is Arcane in its scope (elementalism, evocation, conjuration, psychokinesis, metamorphosis, transmutation, glamor)