OSR: The Only Good Demon is a Good Demon

Ok, the title is a little silly. Let me explain.

In my generic medieval OSR setting there is no cosmic Evil or universal Good. The stage isn't set for an epic struggle between Light and Darkness. The story isn't a fable and it isn't a moral lesson. Instead, like the real world, it's full of people. If evil exists, it is a very human evil, perpetrated for very human reasons. The entire setting is full of people acting on their motives and not for some supernatural cause. or metahuman alignment.

Since people keep asking me why my demons are faithful, I thought I'd write a few notes. To make up for the lack of gameable content I've included plenty of illustrations.

In the Beginning...

The Authority created the world and set the natural laws of Creation in motion. The Authority is omnipotent, but He* cannot change His own laws, lest Creation unravel. He is omniscient, but He cannot see the future, lest time itself grind to a halt. And because Creation is delicate, He sends messengers and lieutenants, Angels, prophets, and saints, to do His will. He has a plan.
*Church doctrine insists the Authority is male.
Mortal creatures have an immortal soul in a body made of matter. This presents a problem; when the body dies or breaks down, where does the soul go? The Authority created Heaven, a realm in the upper air, by holding back some goodness and kindness and peace from the world. This is why things are awful and imperfect; there has to be enough goodness left over for Heaven.

But He took most of the wickedness, cruelty, and violence in Creation and put it deep in the earth, below the stones, where it couldn't trouble anyone. This is Hell. All the torments of the world are like moonlight to the sunlight of Hell's condensed misery, pure, unrefined, and untroubled by cause and effect.

When a mortal creature dies, the soul has several possible destinations. If the creature is sufficiently powerful, the soul might stick around, reanimating the body, reincarnating, flying around, or otherwise causing trouble. For humans and human-like creatures, this state is usually called undeath.

Otherwise, the soul is grabbed by one of the many Angels of Death, examined, and sent to judgement. Souls with uncomplicated histories are sometimes judged summarily. Some require further examination in Heaven.
Souls retain some of the memories of life, trimmed and smoothed and slowly fading. They look like tiny versions of person's body made of soft white light and mist, but they rapidly expand to their original size as residual proprioception kicks in.
Untitled, Justin Cherry


In Heaven, the Authority or His appointed angels judge a soul and decides whether it worked for or against His Divine Plan, and obeyed the laws He gave to mortals through His Church.*
*Opinions vary widely on what exactly these laws are and what you need to do to get into Heaven. The Church is absolutely certain it has it right.
If the soul meets the requirements, great. Heaven is a wonderful, slightly tedious place, and doesn't warrant further description in this article. In fact, it barely warrants description in the Church's doctrine, either except in a negative sense; it's not like this. There is no pain, no hunger, no warfare, no disease. All the troubles and cares of mortal life are are swept away.

And if the soul doesn't meet the requirements, a demon shows up and carts it to Hell.

Hate is my name, Felip Escobar

The Adversary

Someone has to run Hell, so the Authority created the Adversary. She* is not adversarial to the Authority's plan; in fact, She's a vital part of it, and She knows it. She is adversarial to mortals. She is the lamp that casts virtue into sharp relief, the assayer that purifies the base metals. It's a thankless task, but someone has to do it.
*Church doctrine insists the Adversary is female.
The Authority doesn't want people sneaking into Heaven by finding loopholes in His divine rules, or altering his plan by behaving badly. In order to separate true virtue from false-seeming pretense, the Adversary send her legions of demons to torment and test mortals. Angels and demons are the same thing, and often work together on the same problems. They are colleagues from different departments. Demons tend to be a little more mortal-like and comprehensible. They are deeply faithful.

Subtle Theology

The Church takes a very dim view of demons and devils. In the public eye, they are the source of many evils. The Adversary's role as a winnower of souls is mostly forgotten; She is instead portrayed as disobedient and malicious. In the minds of most people, demons are utterly evil. They possess people and drive them mad (it's mostly ghosts and loose spells), they steal cattle (mostly neighbors), cause toothaches (mostly bad diet), nightmares (ditto), and hailstorms (water elementals). They do turn up to tempt and harass people in dreams and visions because that's their job. You can banish a demon by ignoring it and making the sign of the Authority.

There are also tales of witches summoning demons, or of foul pacts with the Adversary in exchange for gold, wealth, or beauty. Demons, of course, encourage these stories as much as possible.

In Practice

You can summon demons. They wrote the books and scattered them around Creation. The dribbly candles and clouds of smoke are just set dressing; the demon is there, waiting, the moment you pick up the book. And they will give you what you want. Gold? Trivial. Beauty? Easy. Power? Sure!

But demons cannot harm the innocent. They will not kill your rival for you. They might show you the way to your rival's chamber, or give you a shiny dagger, but they will also try to arrange things to ensure nobody gets stabbed. You'll be betrayed, discovered, and punished. Demons aren't here to kill people. They are here to tempt people. It's not entrapment, it's a sting operation. They appear in dreams and visions, but can manifest with ease.

People do awful things all the time without any divine intervention or temptation. Demons are therefore very cynical, but they are very proud of their finished products. They might work for years to pry at a secret vice of a bishop, only to wave him happily into Heaven as he dies untempted and unblemished. They don't want people to fall away from divine favour, but it's their job, and people are very eager to fall. Demons keep a running tally of how many people - not starving, desperate, or mad people, just regular ordinary people - have promised their souls for a turnip. It's nauseatingly high.

Rogue Demons

Demons are, by design, willful, inquisitive, and cynical. Their task is very vague and open-ended; they have a great deal of leeway in how they winnow souls. Some demons become rebellious and seek a different life. They try to possess a living creature and hide from both the Authority and their fellow demons. It sometimes works. More commonly, weary demons will disguise themselves are moral guides and try to tempt people back onto the path of righteousness. They are very faithful, after all, and it hurts them to see so many people willingly choose a path that ends in flames and torment.
The Book of Revalation, Chris Koelle

Minor Demons

Straight from the Monster Manual. No stats because the PCs aren't likely to encounter demons anyway. They're only included because people asked.
Don Ed Hardy
Barbed Devil
Appears as a humanoid made from smooth red clay - the blood-soaked ground of a thousand pointless battles. Can grow any weapon from its skin. The Barbed Devils guard the Final Pit, the last gate of hell beyond which there is no return. They are there to scare off souls who might still have a chance at redemption, and to toss in reluctant sinners. They target people who have sworn vows of peace, tempting them with rage or visions of friends in danger. A barbed devil always knows the right words to hurt someone's pride.
Reaper, Bogdan Rezunenko
Bone Devil
Half skeleton, half insect, all legs and scuttling ribs. Alternatively, the corpse of someone familiar to the viewer. Bone devils spend most of their time tempting the virtuous in dreams, convincing them of the horrors of death or their guilt in past crimes. Bone devils love a public confession. Some get overzealous and hound the faithful for minor sins. They love ensnaring people in arguments over minor points, magnifying small difference and flaws into psyche-shattering contradictions.
Demon Sketches, Nick de Spain
Demons (Types 1-4)
Too boring to bother listing. If you have to give your demons numbered types, maybe it's time to rethink your cosmology. The minor angels and functionaries of hell, created for specific tasks, set on specific paths.
Malevolence, Michael MacRae
Messenger angels. They tend to look like whatever the person's culture expects demons to look like, and they show up to cart a soul off to Hell. Their role allows them to be rude, boisterous, and unsympathetic. They appear as backing choruses for the major demons, or in visions to tormented saints and sinners.
N-e-g-e-n-s, Y-mir
Horned Devil
Enforcer angels, sent to deal with particularly difficult souls. They weren't made for subtlety or craft. Each one is like a meteor of chitin and sulphur, full of blades and fire and gold and the howling of firey winds. They are the cruise missiles of hell, set loose at a target, rising from the earth like comets. They are barely self-aware.

Source unknown
Ice Devil
Logicians and planners, but fully empathetic. They are constantly wreathed in frost and steam; their invisible bodies are so cold air freezes on contact, leaving sizzling trails of very confused air elementals behind them. They support philosophers and skeptics in their inquires, sometimes to draw them into atheism and callousness, and sometimes to because they delight in helping others uncover the secret mechanisms of Creation. They also entrap charlatans, false healers, and book-burners.

In the Court of the Hollow King, Alex Konstad
Included for completeness. Penitent souls. Either sliding down to the Final Pit or crawling upwards to the Second Judgement. Thin, wispy things, resembling their mortal shells in a few ways. Sometimes naked, sometimes in the clothes they wore in life. Sometimes wailing, sometimes mad, sometimes grimly determined.

Apocalypse Demon, Piotr Jabłoński
Pit Fiend
The Archangels of hell. Each one was created for a specific task. They slumber in red sarcophagi half a mile high, waiting for the day they are needed again.
Butterfly Angel, Milan Nikolic
They only target people who have made a vow of chastity or fidelity. A wanton stranger from Foreign Parts is safe (from them, at least). A pious Paladin or married shopkeeper is not. They can appear in any form and satisfy any desire. They try not to get into philosophical arguments about doctrine and focus on the physical desires. They will give a few warning shots to pious targets, including a life-draining kiss. In a different guise they secretly give advice to pious orphans. There are no half-demon children (although many parents would claim otherwise).

Significant Demons

The best at their jobs, and therefore the most likely to be encountered. Utterly faithful. They all go to the same Church once a week (and yes, there is a Church in hell. Their guest sermons are something to behold.)
Ignis the Cleansing Fire by legendary-memory
The classic devil in fancy dress. Loves making deals, producing comically large scrolls, signing them in blood, etc. It's all a sham. The contract doesn't mean anything (although Asmodeus will usually follow through, just to make sure the contracted party is properly damned). The sin is making a deal for power or glory. Will pretend to despair at loopholes, vanish, and return to claim the contracted soul anyway - the intent of the deal is more than enough. Scrupulously keeps secrets. Particularly enjoys claiming the souls of diplomats, lawyers, moneylenders, and cheating salesmen.

Occasionally, a righteous person whose prayers have gone unanswered turns to the Adversary in anger and frustration. Sometimes, a demon turns up to seal their doom and feed their vices. Sometimes, their anger is justified, and they are willing to sacrifice their own soul to save others. Asmodeus isn't above tipping the scales a little and providing some secret help, if the circumstances are right. Anyone willing to suffer the torments of hell for purely unselfish reasons might be heaven-worthy.
The Summon, Natasha Nanook

Lord of spectacle and special effects. Appears in a thousand hideous forms, with a thousand equally hideous sound effects. Shocks, frightens, and warns. Cheerfully inventive. Loves all living creatures, but also loves a good jump scare, and knows exactly what everyone is afraid of. Happy to feed fears, paranoia, and guilt. Also in charge of people who try to cheat death or the Authority. It rarely ends well.

Breath of Eternity, Lizzy-John
In charge of liars and hypocrites. One head sees the truth. The other sees every possible lie. They are in perfect agreement. Demorgorgon tempts people away from confession and self-knowledge, giving them every excuse to ignore their own nature and sins until it is too late. Enjoys writing hymns and protecting musicians.

Berserk, Emperor Ganishka
Lord of rules and laws. Every time an cunningly vague law is proclaimed, a mock trial is staged, or an official breaks an oath, Dispater is there (in theory. He's usually busy.) He appears as a crowned demonic king, an ur-father judging from below. His voice is a thousand death sentences. His cloak, a thousand nooses. Dispater doesn't care if the laws of mortals are particularly fair, but he does care if they are broken or twisted by people for their own benefit.He is immensely sympathetic to innocent prisoners and occasionally helps them escape. Similarly, he will offer his aid to criminals, the desperate, and the blood-soaked, only to reveal in the end that it was all a ruse. Their faith in him was misplaced and childish; they should have begged for forgiveness, not for freedom. Remember, demons do not entrap. They only illuminate.
Renekton2, Chenthooran Nambiarooran
Deals with animal and plant souls. Most of the time, their souls evaporate before collection, but a particularly wise tree or a very evil dog might get a place in the afterlife. Creatures that can't choose and can't think can't be punished; you need to know you're breaking the Authority's laws to meet Geryon. He doesn't deal with thinking, complex creatures, and he likes it that way. Has a fondness for whales, beetles, and gut bacteria.
You dare awaken me, witch? Cryptcrawler
Underemployed. In theory, Jubilex seeks out the depraved, the self-loathing, and the utterly amoral and monitors their descent. In practice, it can barely keep up with the inventive drives of mortals. A thousand perversions are attributed to Jubilex - it probably invented two, ever, and they are pretty tame by any estimation. Wryly amused, patronizing, and grimly resigned. Also tasked with monitoring the souls of slimes and jellies (they do have souls, but their thoughts, morality, and religion is completely alien to humanity, and can't easily be explained).
Untitled, Justin Cherry
Deals with escaped souls, ghosts, the undead, and rogue demons. Hell's own inquisitor. Not very bright, but utterly faithful. Has been known to fly to the gates of Heaven itself with evidence condemning a soul, or saving it. In art, a black ram with a man's legs. In reality, an ibis the size of an elephant.
He is the one that rules the sky, Tano Bonfanti
Knows exactly how many angels can dance on the head of a pin. The enumerator, the counter, the designated auditor of the infernal order. If an unexpected soul arrives, he'll be the first to investigate. Looks like a 66 headed hound (the heads overlap like a glass flower). Feeds lost causes and pointless, prideful leaders. Occasionally assists the very, very old, but only if he can find a rule allowing it.
The Molars of Leviathan, Wayne Barlowe

The Structure of Hell

You can walk to Hell. It's below the Veins of the Earth, below everything, but there are stairs and passages and the occasional gate. People have done it. It's not a pleasant journey, and you will not be a welcome visitor in Hell, although your reception will be far less hostile than expected. A faithful pilgrim could pass to the edge of the Final Pit and back without harm.

The Authority ensured Hell has enough space for all time. There are entire vaults that have yet to be opened. All the elements are present, not because they are being punished, but because the elementals obey the Authority, and he required their presence.

Imagine an agglomerate of fossil shells. Then take away the shells. The space that's left is what Hell looks like. There are spirals and curves and plates of half-melted cities. There are halls for lectures, galleries for pain, illusory forests, cascades of fire, and plains of white cold sand. Hell is a mixture, orbiting (at tectonic speed) the Final Pit.

Damned souls can, sometimes, clear themselves of their sin and earn forgiveness through penitence, self-discovery, and clarity. This requires nearly supernatural effort. Most souls don't bother, and slowly spiral downwards towards the Final Pit. Demons will try and pry souls off this self-destructive path if they can, but it is an impossible task. 

The Final Pit contains all the suffering, pain, and horror the Authority couldn't put in Creation. It isn't torture - it's something beyond torture, like sunlight to moonlight. Mortals only live by moonlight.

 Le Pandemonium Louvre, John Martin

Fighting Demons

Any faithful person who makes the sign of the Authority or speaks a heartfelt prayer can banish a demon on the job. There's no point - they'll try again later. It's like hanging up the phone.

A rogue demon is more troublesome and more powerful. And if you need to fight a demon - in a proper fight, for high stakes - don't expect holy weapons or prayers to work. The demons can pray harder than you.


OSR: 12 New Undead Creatures of Varying Power

It can be tricky to think of things for an Exorcist to combat. Here are 12 options. Happy Halloween!

Embodied Undead

Dead bodies animated by a spell or a soul, out of malice or sheer willpower. They can be fought like traditional undead. Destroying the body usually ends the undead's existence.

Ok, this is actually a tapeworm head, but still! Eugh!

0 HD (1 HP): Corpse Snake

Appearance: a rotting stake with three heads.
Wants: to bite the living. Warmth (cannot feel warmth, but still wants it).
Armor: none
Move: normal
Morale: 12
Damage: 1d6 bite, Save vs Constitution or +1d6 poison.

Created by amateur necromancers and desperate spies, or by a hibernaculum starving to death. Can fit in a pouch or bag. Slithers slowly but inexorably. Not much of a threat individually, but they always seem to swarm.

Encounter: a room boot-deep with murky water, and a few corpse snakes.
Encounter: a witch drops one down your chimney. Or puts one in your boot. Or puts one in the stew.
Duty Bound Dead, Johannes Voss

1 HD: Animated Servant

Appearance: a shambling corpse in makeup, with a fine uniform and tarnished buttons
Wants: to obey any command given to them. Not very smart.
Armour: as leather.
Move: normal
Morale: 10 (they sometimes forget they are dead and run away, but then forget why they are running).
Damage: 1d6 pummeling.

Toys made by amateur necromancers, or servants so utterly loyal that death is a minor impediment. Will scrub, polish, carry firewood, serve drinks, and hold torches without complaint. The merest spark of a soul inside, but enough to cause them to sneeze (without a nose) or itch a bit of bone. The little twitches of life.

Encounter: the Baron's old stable-hand died two days ago, but he crawled out of the grave and back to his station. The manor is abandoned. Something has to be done.
Encounter: a pressure plate activates a host of servants with torches, platters, and chairs, setting a table for a feast. The table has long since rotted away to fragments and part of the floor is gone too.

Prince of Persia concept art, source unknown

5 HD: War Spirit

Appearance: a heap of armour and weapons and torn flags shaped like a person. A helm with two burning red eyes.
Wants: to slaughter, to protect tombs and graveyards. Has a territory.
Armour: as plate
Move: normal
Morale: 12
Damage: see below.

A war spirit is created when the last survivor of a doomed unit of soldiers dies. Banners flow together to form a shroud. Swords fuse into misshapen spikes, rings of chain run like water. The war spirit is a hideous, howling thing, and its howl is the shriek of betrayal and iron on iron.

Attacks: Each round, the War Spirit can perform one of three attack patterns.

Swipe. The War Spirit charges forward, swinging its blade in front of it, sending sparks flying. Any targets in front of it must Save vs. Dexterity or take 1d6 damage and be knocked prone.

Roar. The War Spirit raises its head and roars. All creatures who can cover their ears must Save or take 1d6 damage. Anyone who can't automatically takes 1d6 damage. The first time this happens, PCs and hirelings must also make a Save vs. Fear or a Morale check.

Hammer. The War spirit moves towards a single enemy and swings down with a chopping blow, then swipes sideways. This is two normal attacks, each dealing 1d8+2 damage.

Encounter: an ancient abandoned battlefield with a few raised zombies. The PCs come across a thoroughly shredded necromancer, and then hear the rust-roar of the thing the necromancer accidentally angered.
Encounter: a deathtrap maze designed to produce War Spirits. Soldiers go in like grist to the mill. The mad artificers who built it are long dead, but the traps and their end product continue to function.

Xiximanter the Lich, Scrap Princess. From my Tomb of the Serpent Kings module.

10 HD: Xiximanter the Lich

Appearance: Xiximanter is an ancient snake-man wizard, twisted but immortal. He looks like a dried human corpse (with fangs) fused to a snake tail at the waist. He wears tattered robes. His eyes are red pinpricks.
Wants: to continue developing potions, to distill the life-essence of intelligent creatures (preferably wizards), to be left alone.
Armour: as plate+shield
Move: 1.5x normal
Morale: 12
Damage: see below.
Special: If he is in his lair, Xiximanter regenerates 3 HP per round. Xiximanter is immune to all non-magical damage, all mind-altering spells (charm, sleep, etc.), and all curses or persistent enchantments. Lightning, cold, and ice damage deals 1 damage to him instead of the usual amount.
Xiximanter isn't unreasonable, but he firmly believes the snake-man civilization is flourishing, despite evidence to the contrary. He will bargain with any visitors, warn them of minor dangers, and offer them potions to test. If they turn on him, he will fly into a towering rage. He will utterly annihilate one target as an example and try to force the rest of his enemies to flee.

On the first round of combat, or when combat is about to start, Xiximanter will rise to his full height. The lights will dim and his eyes will glow even more brightly than usual. Dark spirits will whisper around him, and his bones will glow with faint magical light. Instead of shuffling, he now moves like mercury. All creatures who see him draw on his full power must Save vs. Fear or flee. He will not attack fleeing creatures unless they have really annoyed him, or they are fleeing deeper into his lair.

Attacks. Xiximanter acts twice per Initiative round; the first time in the usual position, and the second time after all the other combatants have finished. He is an utterly deadly foe in a fair fight.

Heartstop. Xiximanter reaches out with a withered claw, as if holding something heavy and squirming. A single mortal target within line of sight must Save or be stunned for 1 round. If the target Saves there is no mechanical effect, but they are still affected by the spell. If Xiximanter uses this ability on the same target a second consecutive time, the target must Save or die.

Potion Splash. Xiximanter hurls a potion at a target within 30'. This requires a normal Attack roll with a -1 penalty for every 10' past the first. The potion is a random weaponized potion (so a potion of burrowing becomes a potion of melting through the floor, a potion healing becomes a potion of cancerous growths, a potion of raise dead becomes a potion of your skeleton bursts out from your skin and attacks your friends, etc. Not all effects will be Save or Die, must most of them will be Save or Suffer). The potions are weaponized by Xiximanter's hate; once he dies, they become normal potions (but the effects of any weaponized potions remain).

Slash. A normal melee attack dealing 1d6+2 damage.

Shadow Fade. Xiximanter disappears and reappears in any part of  his lair lit by the purple lamps. Any creatures adjacent to him when he reappears take 1d6 damage and must Save vs Fear. He loves appearing right behind people and whispering in their ear.

The following abilities can only be used once per day. These abilities are spells, and can be countered or learned.

Prismatic Lash. Xiximanter swipes his hand through the air, filling a 50' cone with beams of light. All creatures or objects in the area take 3d6 damage, Save for half. Creatures killed by this spell rise as Gibberlings (see below).

Rending Souls. A single target within 10' is grabbed by ethereal hands of smoke and ash. The target takes 2d6 damage. If 12 damage is rolled, or if the target drops to 0 HP, it is torn apart instead (no Save).

Poison Fog. Xiximanter breathes out a cloud of poison fog. It fills a 50'x50'x area. Inside the area, living creatures take 4d6 damage per round and must Save to see anything. The fog tastes awful and burns your mucus membranes. Xiximanter is immune to the fog and can see through it.

Any other deadly spells the GM can think of, invent, or roll.

Possessive Undead

Living bodies inhabited by a second spirit. These undead cannot be fought by traditional means without killing their host. In most cases that might not be enough. Magic weapons and some spells might work, but an exorcism is typically required.

Red Queen, doumyakutosi

0 HD (1 HP): The Ague

Appearance: invisible, but manifests as a fever. If you could see it, it would look like a tick made of glass and fire.
Wants: to grow fat. To spread
Armor: none
Move: as fast as a bird
Damage: 1d4 damage per day, at sunset. Target cannot heal naturally. (Alternatively, use the disease rules of your choice).

A horrible fever with dry skin, tremors, and terrible visions. The Ague is a minor spirit carried on the air. It latches onto a soul like a tick, growing fat on stolen life essence. It is a spiritual disease; those protected by their faith are immune. Wizards are also immune (their souls are lousy with spare spells and cantrips). A strong soul can drive it off, but prayer, ritual, and exorcism are most effective, lest it seek a new host. Alternatively, target the possessed creature with a spell and hope the Auge takes some damage too.

Encounter: one flops out of the swamp and flies in a PC's ear. The fever hits by nightfall.
Encounter: a merchant sells empty glass jars, each one said to contain a trapped ague. The PCs can surely use a disease-spirit...
Asylum Visitor, Bastien Lecouffe Deharme

1 HD: A Passing Fancy

Appearance: invisible, but manifests as an overwhelming compulsion. If you could see it, it would look like a withered head and spine.
Wants: to act out one particular deed, over and over.
Armour: none
Move: as fast as a scrap of fabric on the wind
Morale: 12
Damage: N/A

The remains of some obsessive creature, caught in a spiral of repetitive madness, unshakable habit, or dark desires, and unable to escape them in death. Their desire was stronger than the call of death; now, it is all that remains. It is bound to a specific location or object. Some have haunted families for generations, growing stronger by absorbing the souls of those they afflict, until they are hydra-headed monsters, powerful but still limited in their desires. A creature afflicted by a Passing Fancy might not know it until circumstances present themselves. When the time is right, they must Save or act out the deed that created the spirit. If a Passing Fancy drives a creature to the same level of obsession as the creature that created it, it gains 1 additional HD when the creature it is afflicting dies.

Encounter: a cannibal spirit haunts the wasteland, the last survivor of an expedition. If a companion dies, the spirit demands that the creature it possesses eat its flesh. An afflicted person grows hungrier by the day; only the flesh of friends can truly satisfy them.

Encounter: the Wellenkat family is cursed. Every son murders their father in the same way, on the same night. It's been this way for generations. Wellenkat Manor is nearly fallen into ruin. The PCs are hired to protect the current (very wealthy) dark, brooding, and guilt-ridden Lord Wellenkat from his dark and brooding son. Plot twist: there are dozens of Passing Fancies afflicting the Wellenkat family, plus a few other dark secrets and neuroses.
OM, Justin Cherry

5 HD: Vengeful Ancestor

Appearance: invisible, but leaves wet footprints on moonlit nights. Manifests as an extremely ancient, extremely bad-tempered personality. If you could see it, it would look like a pale and ragged corpse made of glass.
Wants: to live again.
Move: normal
Morale: 10
Damage: see below.
Special: at a minimum, can cast charm person and wither (1d6 to 4d6 damage) once per day. Can improve 2 stats of possessed creature by +2 (improvement can be removed at will).

A ghost that plots to live again. It needs a suitable host (beautiful, tall, strong, wise, etc.), suitable circumstances (usually the night it died), and time to gather its strength. The more closely the target's soul resembles its own, the easier the possession is. If the ancestor was particularly wicked, it will seek a wicked host. If virtuous, a virtuous host - virtue, twisted by obsession, can be a kind of evil. An afflicted person must Save every 4 hours (6 times per day) or allow the spirit to rule its flesh. Each day, the spirit imposes a -1 penalty to Save. The spirit knows many things, and has many skills.

Encounter: a PC visit the tomb of some hallowed ancestor on a propitious night. Their ancestor speaks to them in a dream and invites theirself into the PC's body. They really want to settle some grudges with another family/house/species, and they don't care if there's been peace for centuries. Ancient crimes cannot go unavenged.
Encounter: the dark spirit of Duke Blasphemous visits knights who fall from grace, promising power and skill and advancement. The Duke provides... for a time, but slowly takes over the flesh of the knight to ride again, sowing terror and feeding his own legend. His sign; a black banner torn in half. His mark: a triple sword stroke, like an arrow pointing up. His victims: impaled along the road, with their heads split in half.

Angel78, REYKAT

10 HD: Apocalypse Shell

Appearance: invisible, but cracks mirrors, tarnishes metal, kills frogs, sends dogs howling into the night. If you could see it, it would look like a floating bonfire made of water and blue glass. You can hear it. It's like a second heartbeat pounding in your ears, frantic and irregular.
Wants: to end the world.
Armour: none.
Move: as fast as an arrow.
Morale: 12
Damage: see below.

A spirit that is made, not born. The culmination of a century of rituals, a selective breeding program, an alchemist's mad dream, a fire in a magical library, or some horrible combination of disasters. A city swallowed by a volcano cries out for vengeance at the cruel carelessness of the world. A grieving mother digs something out of the earth and whispers a terrible prayer to the night sky. Perfect love casteth out fear, but, to speak it reverently, so does perfect hate. The Apocalypse Shell is a protoplasmic thing, boiling with half-digested souls, spells, and dreams. It is power incarnate. It needs a host to grow to full strength, and to conceal it from the eyes of the world.

The PCs are unlikely to be chosen as hosts for the Apocalypse Shell, but they might encounter one. The host is usually an innocent, someone who can be driven to a tragic rage at the unfairness, brutality, and pointlessness of life. As the host lashes out at the world, the Shell will unfold, and the world will end in fire and blood. Until then, it is kept safe and usually restrained.

Attacks. The Shell makes 1 attack per round if threatened. It makes 1 attack per week if not threatened.  This is usually how people find it.

Wail. 200' range. 2d6 sonic damage within 30', 1d6 damage up to 200' away, and audible for two miles in clear weather. Shatters glass, cracks stone, bursts eyes in their sockets. Creatures that can cover their ears can Save for half damage.

Buckle. Reality warps. Gravity reverses, then flips back. Any loose thing within 50' is briefly tossed into the air. Most of the time, this doesn't deal any damage, but unprepared PCs standing near ledges or in rooms full of flasks of acid might take damage. If the Apocalypse Shell senses a threat, it will target one person with this ability, dealing 2d6 damage and flinging them 50' in any direction. Save negates.

Rend. Something tears in half. This could be a PC, a wall, a farmhouse, a glass jug, or a cow. It's messy. Save negates, but means a nearby object tears in half instead.

Boiling Buzz. A swell of magical power, on the edge of hearing and thought. It grows like a swarm of invisible locusts, cutting and clawing and sizzling. All spells within 200' flee the heads of any spellcasters. They have a 1-in-6 chance of being cast on a random target as they flee. All creatures must Save vs. Wisdom each round or be stunned. The Apocalypse Shell can maintain this ability indefinitely, but cannot perform any other attacks while maintaining it.

Disembodied Undead

Ghosts, ghasts, shadows, and revenants. Things that live on without a body, and don't need a body to live. They can only be damaged by magic weapons or certain rituals, but they can be fought and banished. They are usually immune to a wide variety of spells.
Topplegeist, Seb McKinnon

0 HD (1HP): Gibberling

Appearance: mostly invisible, but pops in and out of vision. Looks like a ball of mist with a half-formed face.
Wants: to touch things, to knock things over, to undo knots
Armour: as leather
Move: 2x normal
Morale: 6 (will sulk and return later)
Damage: 1d4, ignores armour

The ghosts of people or animals killed so swiftly they are not aware they have died, but with insufficient willpower to remain whole and cohesive. Usually magic is involved (or guns or explosives, if your setting has those). A Gibberling doesn't know what it is or where it is or what it wants to do, so it reaches out in idle frustration to ruin the plans or happiness of people nearby, in half-understood envy. It is only as strong as a newborn, but it can still undo knots, turn pages, tip over candles, and generally inconvenience people. Usually, Gibberlings last a few days or weeks before fading. They can be scattered by funeral ashes and scared away by prayers.

Encounter: a village was wiped out in the night by some unseen disaster; a curse, a swift disease, a burp of CO2 from a volcanic lake. The entire place is infested with Gibberlings. Hundreds of them.
Encounter: a climbing party fell to their death in the dark, and the bottom of the pit is filled with the soft grey mist of the Gibberlings. They aren't dangerous... until the PCs try to climb out.

Save Me, Konstantin Kostadinov

1 HD: Faded Memory

Appearance: mostly invisible, but sometimes, as they were in life, but distorted, ethereal, translucent, grey. They move slowly, gracefully, as if underwater.
Wants: to play out some half-remembered fragment of its life

Armour: as plate
Morale: 12
Damage: 1d6, drains 1/4 level XP or does some equivalently horrible thing. Ignores armour.

Some spirits remain out of grief, or guilt, or madness. There's no reason to it. No unfinished business, no drive. They simply refuse to depart. They drift slowly, acting out their last days, seeing nothing, thinking of nothing. Their attention can be attracted with difficulty; it is rarely worth it. The swat aside distractions with murderous haste, then return to their burned-in path. Their touch kills if they want to kill. Otherwise, it's just cold mist.

Encounter: a noble's child is sick; each night it grows weaker. Doctors and wizards are baffled, but an old priest suspects the work of a ghost. A nurse was killed in the house years ago. Each night, she visits the child's crib to tend to it. Uncovering the secret will embarrass a lot of powerful people.
Encounter: a ruined castle, detested by the villagers below, filled with the ghosts of courtiers, servants, and nobles, acting out a silent life. They were slaughtered in a single hour by a powerful sorcerer, who remains trapped in the castle's throne room, unable to leave because of the throne's protective curse.

Immortality, Chenthooran

5 HD: Gestated Guilt

Appearance: mostly invisible, but can appear in two forms. A hideous, amorphous, cancerous thing, made from ash and black tar, or the idealized form of the creator's guilt.
Wants: to get revenge on its creator, in a strange half-understood way.

Armour: as plate
Morale: 12.
Damage: 1d6, drains 1/4 level XP. Alternatively, 2d6, throws target 10'.

Not all ghosts come from the dead. Guilt, over many years, can form a sort of pseudo-soul. A guilty person can split their own soul in half, feeding a separate entity on misery and self-loathing, until it becomes a fully separate and dangerous creature. It's a self-destructive spirit. It will lash out to destroy its creator and anyone near them, as its creator watches helplessly and, possibly, with a sense of relief.

Encounter: a priest drowned his lover in a pool. He believes he's being haunted by his lover's spirit. The manifestations have become increasingly dangerous and he begs the PCs for  help. The spirit is very dangerous indeed, but it can't be killed normally; the priest will regenerate it, larger and angrier than ever, and slowly grow weaker in the process. Killing him will banish the ghost forever, but he's the only one who knows where the treasure is buried, and he's not stupid enough to tell the PCs until he's certain the ghost is gone.
Encounter: a local noble believes the spirits of his assassinated family are stalking him. His madness has created one ghost; his violent deeds created another. They work to torment him together by blighting all he hoped to gain and all he holds dear. Can the PCs save him from a matched set of ghosts?

Queen, SaeedRamez

10 HD: The Umbral Duchess

Appearance: mostly invisible, save by the light of the thinnest possible crescent moon. Then, a castle on a hill, with white banners and grey stones. Inside, empty halls, save for an assortment of ghosts, spectres, and shadows, and the Duchess.
Wants: to rule, to be obeyed, to cause the suffering of her rival clan
Armour: as plate

Morale: 12
Damage: see below.

She was entombed in her castle and left to starve, but death did not carry her away. She remembers her stronghold and it grows from her soul. She was a powerful wizard, in secret. A wise ruler, in public. But the times changed and she was entombed. When she died, she rode out on her pale horse, and the grass died beneath its feet. The path can still be seen and followed. She rode to the castle of  her enemies and swore a terrible oath. She would kill every member of their household unless the first child born to any heir was sent to her castle to starve to death in a crypt. But not in infancy, but just before they came of age, just when they expected to be accepted into the family.

And then she drained the life from her tormentors, just to make sure they got the message, and left their withered bodies on the floor. Perhaps the PCs have come to beg for her aid or her wisdom. Perhaps they have come to rescue the doomed heir. Perhaps they merely blundered into things. There is no treasure here. She will treat visitors courteously as long as they honour her properly. She will tolerate minor rudeness and ignorance, but questioning her current state, her desires, or her power will result in slowly rising anger and, probably, a horrific death for the PCs.

When combat begins, or when the Umbral Duchess is sufficiently annoyed, she becomes invisible and then flies towards a PC, appearing only at the last second, all the while howling in misery and range. All creatures witnessing this must Save vs Fear or flee. Fleeing creatures must Save a second time or suffer the Soul Drain effect below. Particularly devout people may be immune to both effects.

Attacks. The Umbral Duchess acts twice per Initiative round; the first time in the usual position, and the second time after all the other combatants have finished. Without proper protection the PCs are likely to be annihilated.

Soul Drain. Target creature within 30' must Save or lose 1 level of XP and be stunned for one round. Their hair goes grey immediately and they age 2d10 years.

Caress. The Umbral Duchess moves to any spot within 30' and makes a normal attack against the target, ignoring armour. If she hits, she deals 3d6 damage. Creatures killed in this way rise as Wights under her control.

Guilt. Target takes 1 damage for every innocent person they have personally killed or ordered to be killed. If this damage kills the target, they are dragged screaming into the afterlife.

Spell Reflection.
The Umbral Duchess casts the last spell that was cast on her, but with 1 extra level/magic dice, or otherwise improved, and with a few minor flourishes of her own invention.

The Umbral Duchess moves to any spot within 30' and makes a normal attack against the target, ignoring armour. If she hits, the target is frozen for 3 rounds. It cannot speak or move. After the 3rd round, the target may Save to break the enchantment.

Flesh Peel. Only used on helpless or frozen targets, or the wounded. Target takes 1d6 damage as their skin and flesh fall away in long, easy-to-chew strips.