Dungeons & Dragons has its fair share of Eldritch Abominations, varying in size and severity, from the kind your players might have a chance against if they get some lucky rolls, to the kind that consumes universes for funsies. Note that several settings have their own specific abominations. All have been gathered here for simplicity's sake.
Aberrations and Things from the Far Realm
- The multiverse features several examples of world-enders from virtually every plane, but the most eldritch ones originate from the Far Realm, an Eldritch Location of infinite madness and horror. It has no place on the Great Wheel, World Tree or World Axis cosmologies, because it defies any kind of categorization. Limbo may be weird, but you can boil it down to just "The opposite of Mechanus". The Far Realm has no such simplicity. It's assumed that just going there would cause permanent madness, if not outright death. Aboleths originate here (see below), as do several Elder Evils.
- 3.5 edition had an entire Splatbook specifically about eldritch horrors called Lords of Madness. Aboleths, Beholders, Illithids, Grell, Neogi, and a new monster called the Tsochari got their own chapters, and it also introduced a large number of other horrific monsters to the game.
- Aboleths from the Far Realm are on the lower end of the eldritch scale, but still powerful enough to pose a legitimate threat to virtually anyone. They look like really weird fish with three eyes placed on top of each other, have extremely potent psychic powers, are nearly immortal, and their ancient empire predates the gods. When a new aboleth is born, they inherit a copy of all of their parent's memories, so all of them are able to remember a time when they ruled the world, and they want to take it back.
Readers will notice a thematic resemblance between the aboleths, the Elder Evils, and various creatures or beings found in the stories of H. P. Lovecraft. This is, of course, completely intentional.
- Aboleths worship nothing, but they respect beings they call the Five Elder Evils. These are thematically based on H. P. Lovecraft horrors and include flames surrounding a body that will drive you mad if you see it (if it does not kill you outright), a ball of sentient goo the size of a planet, and a drilling subterranean squid/centipede thing that appears to be eating its way very, very slowly through the crust of the planet, whose feces will make your head go wonky if you get too close to it.
- 4e suggests that aboleths aren't even intelligent, thinking creatures; rather, everything they do is the result of a guiding, species wide instinct that is unfathomable by mortals. 3.5e and the previous editions, on the other hand, state that aboleths are intelligent and thinking beings, but operate on concepts entirely beyond mortal comprehension; their intelligence is described as a vast and endless ocean, while that of a regular human is but a drop of water.
- Aboleths have enough parallels to abominations of the Cthulhu Mythos that the question was directly addressed in the Lords of Madness sourcebook:
- The Beholder. A floating orb thing with one big eye, and several smaller ones on eye stalks. Each eye stalk can send a different ray (petrification, charm, damage, etc.), and the big eye in the middle prevents magic from working in its area of effect. And that's not the weirdest thing: it is revealed in 5th edition that when a Beholder dreams, its dreams alter reality, which can cause momentary changes in the immediate area, but can also spawn new Beholders, the weaker Beholder-kin, or change the Beholder itself. The world itself may be a Beholder dream, Azathoth style.
- Whats even more eldritch about Beholders is that they, like other species, can be "normal" zombies, but if a Beholder dreams about existing beyond death, it gets weird. Death Tyrants lose all their skin, including the tentacles, leaving behind a skull with floating dots for eyes. The eyes retain their abilities, but the central eye gains a new one: People affected cease all healing. Whether through magic or natural causes, all life ceases, and what dies become zombies under the Death Tyrant's control.
- The Gibbering Mouther is the most well known and reviled example of the horrendous Aberration type creatures hailing from the Far Realm, a Blob Monster with Too Many Mouths and eyes in weird places whose constant gibbering induces Brown Note and sucks blood from its victims. Plus, some excerpts directly reference Lovecraft's own Shoggoth, of which it perfectly resembles.
- It is revealed in the 4th edition that the Gibbering Mouther is actually the weakest type of a group of monsters called Gibbering Beasts. The stronger kinds are the Gibbering Abomination, which looks like a more solid Mouther with tentacles that also has Eye Beams, and the Gibbering Orb, which looks like a floating sphere of eyes and mouths that have even more Eye Beams. And even though Gibbering Beasts seem like they are completely insane, they actually are quite intelligent and may work with other kinds of Aberrations to accomplish mysterious goals.
- The Kaorti were once a group of wizards who traveled to the Far Realm to study it, but ran into an Elder Evil called Zurguth, The Feasting Vast. Zurgurth transformed the wizards into inhuman monsters by accident, just by examining them. Now the Kaorti are invading the material plane and working to make it more like the Far Realm.
- The only thing that Aboleths are really disturbed by are the brain eating Cthulhumanoids known as Illithids, simply because Aboleths have no idea where they came from. It turns out the reason for this is because Illithids actually came from the distant future, close to the end of the universe.
- Mordenkainen poses the theory that the Far Realm isn't simply a single place; rather, it's an entire multiverse, akin to the one that all campaigns take place in, except it's just... wrong.
From the Outer Planes
- Neth, The Plane That Lives. A whole demiplane that is alive, introduced in The Manual of The Planes. It qualifies as both an Eldritch Abomination and an Eldritch Location. The Far Realm suggests that it contains creatures possibly just as large or maybe even larger, leading to the idea that Neth is one such native of the Far Realm that just so happens to have a portal to the Astral Plane inside itself. It learns by absorbing the denizens of other Planes that visit it.
- In Planes of Conflict it is briefly mentioned that travelers between the orbs of Carceri occasionally hear distant music which lures them further into the void. The only individual who survived this experience claims to have seen gargantuan monstrosities whose imprisonment predates that of the titans.
From the Nine Hells of Baator
- One of the various backstories of Asmodeus, the Lord of Nessus and King of Hell, is that he is actually one of these. What others see when dealing with him is actually an advanced illusion. Asmodeus' real body is that of a titanic, hundreds of miles long serpentine creature named Ahriman who is still injured from his crash landing in Hell. He was some sort of primordial entity who predated the Gods, and either was thrown into Baator by the gods or crashed there after his struggle with his twin sister Jazirian (who seems to have become the god of the Couatls Always Lawful Good winged serpents since then). In the latter case he fell so hard that when he hit the bottom of the seventh layer (Baator initially had seven layers), he fell through it and created the eight layer, only to fall through that as well and land on the ninth layer, where he came to a stop at the bottom of an impossibly deep canyon created by his fall.
- While he is still injured by the fall, he found a way to recover: by feasting on the souls of unbelievers he regains his power to the point where he can break free from his prison of Baator and remake the multiverse in his image. Fortunately, people who do not believe in anything are rather rare in the setting and Asmodeus can gather this energy only in trickles over the course of centuries. To both increase the number of unbeliever souls and to deceive those who would stop him, Ahriman created Asmodeus to divert attention away from this fact. Everything about him and his actions, from his status as an angel, his fall, the Blood War and the politics of Hell are nothing but a sham designed to keep everyone occupied and freeing a lot of Asmodeus' time to be able to plot to increase the numbers of unbelievers to feed on. And the worst part? It's working.
- Expanded upon in The The Gates of Hell fan supplement. Asmodeus is the Prime Force of Lawful Evil, who initially was part of a circle of three beings. Once their disagreements on how to arrange the multiverse caused them to separate, Lawful Good was flung up and created Heaven, Lawful Neutral was flung sideways and became the cogs of Mechanicus, and Lawful Evil was flung down. That fall didn't create two of Hell's circles, it created all of them. The Ancient Baatorians, the Malefircareim, were formed out of his blood, each a demigod. Then, a trillion or so years later, the Overlord awoke, found his "children" to be too independent, and created an avatar to put them in place. That wasn't Asmodeus; he was named Lucifer. The final battle was Lucifer against nine million of the demigods, and it was a Curb-Stomp Battle. He spared a few to become the Lords of Nine and other noblemen, and created a hierarchy of weaker devils, from lemures to pit fiends note . A couple trillion years later, the Overlord grew wary of gods opposing him, so he created a second avatar, Asmodeus, and "overthrew" Lucifer, to make Hell appear less threatening. When a devil who aided Asmodeus, who also happened to be his wife, suspected something and wanted to know more about him... well, she was never the same after he showed her, ultimately getting killed while attempting a literal Brain Bleach. Now, what is the Overlord doing with his time? He feeds upon mortal souls in order to heal his real body. How big is the body? Not hundreds of miles. It is a winged serpent which can fit the entire Earth on a single one of its scales.
- Before Asmodeus even landed in the Nine Hells, they were inhabited by the Ancient Baatorians. Hardly anything is known about them, since they appear to be resistant to both scrying and divine magic, and because Asmodeus has done his best to remove record of their existence from existence. They still occasionally manifest as indestructible, shapeless forms that breathe in light and breathe out darkness. Some of them even breathe life rather than light. Some say the Ancient Baatorians aren't even alive in the same way that both devils and mortals are they're more some kind of formless primordial entity that can only partially manifest under certain conditions and in certain places. More strangely, the realm of Baator itself seems to be involved in their generation nupperibonote will evolve into an Ancient Baatorian over a very long period of time, which is why more powerful devils destroy nupperibo when they can. There is however one ancient Baatorian who did survive: Zargon, who appears in the book Elder Evils.
From the Abyss
- One could argue that the Abyss, a Layered World upon a Layered World, is a similar kind of living Eldritch Location. Many of the levels of the Abyss are certainly alive and thinking, the 92nd layer itself being no more than a giant tentacle monster called a Draeden. However, it's made clear that the Abyss as a whole, and the Demons that live within, are a single entity. It's inferred that the already infinitely deep Abyss feeds on the other dimensions around it, absorbing them into its mass. And whats worse is that It's growing even bigger.
- The Obyrith were the demons who ruled the Abyss before the Tanar'ri; they existed since before the dawn of time or at least conventional mortal life, often have incomprehensible biologies, and just glancing at one is enough to induce new phobias or temporary insanity. One of the oldest still extant, Pale Night, horrifies reality itself to the point where reality hides it behind a series of ripples in existence making her seem like an otherworldly woman hidden behind a series of veils and can kill if you get a glance at her true form.
- Dread Tharizdun originated in the Greyhawk setting, but eventually came to be a bit of a Greater-Scope Villain for D&D in its entirety. Tharizdun was originally a god; in fact, he was one of the first gods. After the Dawn War, the Obyriths started whispering to him about how he could become all powerful and rule the entire universe if he just did them a small favor: take a little shard of ultimate evil, and plant it in the Astral Sea. Unfortunately (or fortunately), Tharizdun was smart enough to realize the gods would instantly stop him if he tried something like that, so he instead took the shard to the middle of the Elemental Chaos, the plane of origin for the Primordials, and planted it there; that shard grew into the Abyss. The gods realized what he had done, and tried to kill him, but the shard had given him power to rival every other god, so they couldn't do much more than imprison him in his own personal hellish universe (where its own version of the Abyss had already won).
- Demogorgon, known as the Prince of Demons and Lord of Madness, is the most powerful demon lord. It has vaguely reptilian legs, with tentacled arms, and the upper body of a primate. Its two heads are both batshit crazy, even by demon standards. The leading theory among demonologists is that it seeks to destroy everything in the universe aside from itself, and once it's alone, its two heads will consume each other. Demogorgon was the very first tanar'ri demon created by the Queen of Chaos and so is the most eldritch of them, while most tanar'ri demons resemble more familiar beasts or simply take the classic Big Red Devil look.
- Other Tanar'ri, on the other hand, resemble the shapes above, and some demon lords can be truly eldritch. Take, for instance, Zuggtmoy, demon queen of fungi, the lady of rot and decay. She usually takes the shape of a woman made of fungi, but even in that shape she's unsettlingly thin, and there's a wrongness about her. Her personality isn't much better: As the demon prince(ss) of fungi, her attitude is utterly inhuman in every way. Her only concern is to spread her spores, wanting to make the entire multiverse into a super organism with her on top.
- Another demon lord that fits high on the eldritch scale is Juiblex, demon prince of oozes, the Faceless Lord and Lord of Nothing. A vaguely green ooze covered in eyes who rules over all oozes and other shapeless things. Unlike other demon lords, who are at least somewhat involved in plotting, even the deranged Demogorgon, Juiblex cares nothing for anything, only wanting to consume. Not even out of hunger, it simply desires to consume everything around it until it lives in a world of only slime. All demon cultists are mad, but one would have to be utterly insane to worship Juiblex. And according to some sources, Juiblex may just be an aspect of a much worse and incredibly ancient evil god of slimes and aberrations called Ghaunadaur.
From the Inner Planes
- Elder Elementals from the Mordenkainen's Tome of Foes sourcebook. Basic elementals are creatures made from the different elements. These elementals are that taken to its logical extreme. They're also so dumb that they probably won't notice you until you attack it. That doesn't mean they won't cause enough destruction that you'll probably not have a choice but to fight it, however.
- The Leviathan (not to be confused with the Elder Evil below) is an enormous sea serpent made from water. It can smash ships with little to no effort, create tidal waves in a few seconds, and moves like lightning under water (120 feet in 3 seconds). Its only real weakness is that it can freeze over, and even that only slows it down.
- Elder Tempests are basically thunderstorms with wings and something resembling intelligence. Its lightning will probably kill you if it passes by.
- Zaratan are a slightly less lethal Tarrasque. Massive earth creatures that just walk around and destroy, without even knowing it.
- The phoenix may be the worst. While the others cause destruction mostly by accident, the phoenix is actively looking to destroy. And even if you kill it, it will probably cause twice as much destruction with its death.
- And even worse? All of them can be summoned, like any other elemental. Anywhere. Someone could be performing a ritual to summon a Zaratan under the streets of Waterdeep, and you wouldn't know until Waterdeep suddenly sits on the back of an earth turtle.
From the Prime and Transitive Planes
- Tarrasque. A Kaiju and Godzilla-expy widely considered the strongest beast in the world. Only one exists, and it alone is enough to make the gods fear. In the Forgotten Realms, it was created by the Primordials as a biological weapon during the Dawn War, and it certainly shows. It's death requires more damage output than most parties can scrape together at level 20, and in most editions, it's never quite dead.
- The Epic Level Handbook for 3rd edition brought us the Abominations, malformed offspring of deities which desired to destroy all reality. Among the most horrific of them are the Atropal, which are the undead remains of stillborn godlings.
- Several other monsters from the book qualify, such as the Neh-Thalggu brain collectors (who collect brains), the Uvudaaum, who are powerful enough to reign as Sorcerous Overlord over sections of the Far Realm itself, and the epic version of the pseudonatural template, which represents creatures that are either heavily corrupted by the Far Realm's taint, or are actually attempts by the Far Realm to imitate "normal" lifeforms, which tend to fail. Badly.
- 4th Edition has the Primordials a primeval race of elementals who created the universe (depending on the setting. In others, they are simply rivals to the gods) and are powerful enough to destroy gods. They would like nothing more than to destroy said creation, since as their nature as elementals dictate, they wish to continue an endless cycle of death and rebirth.
- 4E gives Warlocks the Star Pact power source, which involves beseeching strange otherworldly creatures that lurk behind specific stars for power. A lot of fluff text suggests that they become a little unhinged. Furthermore, a Dragon Magazine supplement includes an Epic Destiny where you become one of these strange otherworldly entities. It also describes the aforementioned stars and notes their "unnatural" qualities, particularly one that you're better off not looking at for long.
- The stars themselves are Eldritch Abominations in 4th edition. And some of them have the ability to create avatars of their power, to the point where even black holes can create such avatars. Luckily, at least one of those stars is good: Ulban the Messenger is a mostly benevolent comet god who wants to change the future, but his Star Spawn, featured in the Monster Manual Three, is evil aligned.
- An entity that actually exists on Oerth itself is the Mother, a bizarre entity served by a colony of degenerate and inbred humans who found it while they fled the destruction of their old empire. Physically, the Mother looks like a large mass of disgusting white ooze that slithers across the walls, floor, and ceiling of the caverns it inhabits, with the ability to drain the life out of anything it makes physical contact with. Unlike the other examples, it's possible for the Player Characters to actually punch the Mother out, as it's mentioned in one of the adventure ideas provided by Gary Gygax in the original 1983 Greyhawk boxed set.
- The D20 setting DragonMech has the lunar gods, mysterious entities from the rapidly-descending moon. There are three main ones: Andakakilogitat, lunar god of dragons, a squirming mass of dragon parts; Erefiviviasta, lunar goddess of flightnote , who is not described; and Seroficitacit, god of change, which is a perpetually mutating and somewhat insane mass of flesh.
- Warlock players can gain their powers from one of these, with the Great Old One's pact appearing as early as the player's handbook in 5th edition. As you might expect, the pact grants telepathy and various Lovecraftian Superpowers, and Cthulhu is explicitly noted as a potential patron. The Fathomless patron may also fit this trope, being a creature of the bottomless seas.
- The 3.5th edition sourcebook Elder Evil contains guides on how to make one of these for your campaign, as well as a list of a few pretty horrific ones to use as you wish. Each come preloaded with their own Signs of the End Times.
- Atropus is probably the most horrific of the Elder Evils. It is a moon made of god knows what, with massive geological marks forming a giant, screaming, skeletal face. It's origin is unclear, and varies depending on the setting, including being the quasi sapient head of the god who created the universe and hopes to finally die, a literal stillborn god, and the head of a primordial, but the most popular theory is that it is an undead afterbirth of the creation of the universe. It's arrival increases the effectiveness of necromancy all over the world, until everyone who dies become zombies, whether someone reanimates them or not. The only imaginable way for the players to even remotely challenge it is to fight a manifestation of its consciousness, weakening it enough for the gods to come finish it off. The book suggests that the only way to kill it once and for all is to throw it into the Positive Energy Plane.
- Father Llymic is a being from the Far Realm that radiates cold when exposed to light. The ancient elves exploited this by putting him on a mountain, but his prison has started to weaken. The sun's rays are weakening, and Llymic's brood, which consists of creatures infected by a disease that makes them more like Father Llymic, is prowling the countryside. Villages near his mountain have been abandoned due to the cold, and there are sightings of an old man walking the empty streets, beckoning people towards the mountain...
- The Hulks of Zoretha are the least eldritch of the elder evils, but are still an apocalyptic threat like all of them. The Hulks are five giants from another world who plan to exterminate all life on the planet so they can repopulate it with their own kind. They are currently asleep, but as they get closer to waking up, the moon turns red, causing everyone in the world to be affected by uncontrollable rage, throwing the world into chaos.
- The Leviathan is on the lower end of the scale, but still pretty horrific. It is a massive sea creature, one spike big enough to contain an entire temple, made from all the leftover destruction from the creation of the universe.
- Pandorym is an intelligent super weapon from another reality that was summoned by a group of wizards who wanted to threaten the gods. The wizards trapped it by separating its mind from its body, and sealing them away separately. While its disembodied mind looks like a cloud of smoke (with tremendous psionic might, such that coming in contact with it risks complete mental domination), its body is a Sphere of Annihilation, a hole in reality that destroy anything it touches like a black hole. If it were ever made whole, it would be completely unstoppable.
- Ragnorra, the Mother of Monsters, is an entity of corrupt life energy that travels between worlds in the form of a comet. She horrifically transforms all life on any planet she visits to fit her own twisted ideals of what life should be.
- Sertrous is an ancient Obyrith demon prince who takes the form of a snake with a five jawed head. He is the being responsible for revealing the secret that divine magic doesn't require a god as a source of power, making him a another Satanic Archetype character. Though he currently is dead, as more people start worshiping him instead of the gods he gets closer to coming back to life.
- Kyuss, the Worm That Walks, was a evil prophet who attempted to achieve godhood by sacrificing all of his followers and merging with an ancient obelisk. He didn't entirely succeed and got stuck in the obelisk. He takes the form of a giant made worms, and if he is unleashed it will result in the beginning of the Age of Worms
- Originally from the early adventure B4: The Lost City, Zargon the Returner is the former ruler of hell who was overthrown by Asmodeus. He is only still alive because not even the gods could kill him permanently, as if he is killed he will just regrow from his indestructible horn. He looks like a one-eyed, one-horned, giant with tentacles in place of limbs, and his touch can turn people into ooze monsters.
- Forgotten Realms has three monsters that are also considered Elder Evils.
- Dendar the Night Serpent is a massive snake said to be born from the first dream. She grows stronger by consuming nightmares, and she is destined to one day destroy the entire solar system of the Forgotten Realms setting when she has grown strong enough.
- Kezef the Chaos Hound looks like an enormous dog whose flesh has been replaced with maggots. He was either created by or released by the setting's old god of death. He devours the souls of the faithful in the afterlife and is powerful enough that even the gods fear him.
- Ityak-Ortheel the Elf-Eater is the most alien of the three. It looks like a gigantic turtle, but with only three legs, and in place of a head is a mouth surrounded by tentacles. It was born from the spilled blood of two gods, and it hates all living things; it also only feeds on the souls of elves. Being mostly unintelligent, it is used as a living superweapon against elves.
- The Daelkyr, extra-dimensional invaders who mess with the fabric of reality for shits and giggles. They also like to mess with mortal biology like a kid plays with Play-Doh. And their plane of origin, Xoriat, is Eberron's cosmological equivalent to the Far Realm.
- For some reason, all of the six Daelkyr who were trapped on Eberron look like unnaturally handsome male humans with one feature changed. The Master of Silence, the Daelkyr Big Bad in The Dragon Below' Trilogy, has smooth skin where his mouth should be. According to Word of God, the question is not to ask why Daelkyr look so humanoid, but to ask why humanoids look so Daelkyr, though it was later clarified that this was a joke and that nonhumans see them as looking similar to themselves.
- Speaking of Eberron, there's also the Quori, horrifying monstrosities from the plane of dreams with very strong Psychic Powers (usually of the Mind Control or Mind Rape varieties) and the ability to possess mortals. They have already conquered/subverted almost a continent and would really like to take over the rest.
- While it mostly deals with Gothic horror, the Ravenloft campaign setting features an eldritch abomination in the form of Gwydion the Shadow-Fiend, Darklord of the Shadow Rift. He became trapped between realities when a planar gate collapsed on him, and really, really wants out. His full appearance is unknown, but what has been seen causes even The Fair Folk to go mad.
- The Dark Powers, the force(s) that created Ravenloft itself, actual nature, methods, and motives are entirely unfathomable; the Nightmare Court could also qualify.
- Regular old fiends (demons, etc.) were described in eldritch abomination terms in Van Richten's Guide to Fiends for this setting, being horrifying creatures of great power and alien minds from other realities.
- Many of the Cthulhu Mythos deities (such as Cthulhu himself) have entries in the 1st edition Deities & Demigods supplement and the way 1st edition rules worked, a high enough leveled player character could, in fact, punch them to death.
- Basic D&D was no stranger to Eldritch Abominations. Aside from the Nightmare creatures (like the Diaboli and the Malphera), whose physiology was utterly alien and horrific to humanity, there were also the creatures from the Vortex, a place beyond all dimensions and planes of existence, who could cause inexplicable phenomenons with their mere presence. Even the Immortals are afraid of such things.
- The Immortals Handbook: Epic Bestiary 3rd-Party rulebook, designed to make the best of the Absurdly High Level Cap features the "Nehaschimic Dragons", beings who are described as "nightmarish interdimensional creatures extraneous to the universe itself... transdimensional tapeworms writhing within the body of the [universe], a surreal symbiosis of reality and unreality". In the rules, all Nehaschimic Dragons have the 'Alter Reality' power, extremely high Damage Reduction, immunity to all but a few specific types of magic and elemental damage, can travel at the speed of light (or faster), see all the way to the edge of their current universe, grow to become bigger than the universe (at least from your perspective) and their very presence causes permanent insanity for everything within miles. They also far exceed most other monsters in sheer size; the largest are well over a quarter mile long, at least as far as their stats are concerned. Unfortunately, or perhaps fortunately, there was only one Nehaschimic Dragon ever published, the Nexus or Wormhole Dragon. It has a Breath Weapon with a flat 50% chance (or higher) to shunt you into an Alternate Universe, power over probability, and an aura of "Unknowing" which can even cause the universe to forget you if you're weak enough. A few others have been unofficially published online, and are just as weird, if not more so, than the Nexus Dragon. On the forum which discusses possible ideas for these books, one person suggested an adventure where a planet needs to be evacuated because it's a dragon egg about to hatch. The poster eventually made the idea into dragonsnote which are the nerves of the Akashic Records (the one power above God, basically). Their flavor text is about a Multiversal Conqueror who has just crushed the God of another universe... and then he sees one of these dragons. It ends with him realizing that the almighty artifact around which he built his empire is merely a scale said dragon lost.