Dungeons & Dragons have 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 bellow), as do several Elder Evils.
- 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, collective memories, actual immortality, and their ancient empire predate the gods.
- 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.
- While 3.5e and backwards states 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. See Blue and Orange Morality, or Lords of Madness.
- Aboleths have enough parallels to abominations of the Cthulhu Mythos that the question was directly addressed in the Lords of Madness sourcebook: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.
- Behold the Beholder. A floating orb thing with one big eye, and several smaller ones on eye stalks. You've probably seen them before. 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. That's not the weirdest thing. When a beholder dreams, its dreams alter reality. This can cause momentary changes in the immediate area, but it can also spawn new beholders, the weaker beholder-kin, or change the beholder itself. The world itself may be a beholder dream, Azathoth style. And don't even get me started on the undead ones.
- Too late, you got me started. Beholders 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, all life ceases, and what dies, become zombies under the tyrant's control.
- The Gibbering Mouther is the most well known and reviled example of 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 turns out that the Gibbering Mouther is actually the weakest type of 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. Although 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.
From the Outer Planes
- Neth, The Plane That Lives. A whole freaking 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.
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.
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 worse yet, 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, he could rule the entire universe, if he just did them a small favor. Take this little shard of ultimate evil, and plant it in the Astral Sea. He could do that, right? 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 to imprison him in his own personal hellish universe (where its own version of the Abyss had already won).
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 it's 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 fight it, however.
- The Leviathan (not to be confused with the Elder Evil above) 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 Tarraque. 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. Kaiju, 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. Where is your god now?
- 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.
- Really, several other monsters from the book qualify, such as the Neh-Thalggu brain collectors (guess what they do), 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 (trolls should not look like that).
- 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.
- 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 are as elementals dictate, they wish to continue an endless cycle of death and rebirth. Most mortals are perfectly fine with the world as it is now, especially since said death and rebirth would include them.
- 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. And 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 was featured in the Monster Manual Three, and oh looky, it's evil aligned.
- An entity that actually exists on [[Tabletop Game/Greyhawk 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.
- 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.
- 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 is prowling the countryside. Villages near his mountain has been abandoned due to the cold, and there are sightings of an old man walking the empty streets, beckoning people towards the mountain...
- 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 setting, but includes the quasi sapient head of the god who created the universe, hoping to finally die, a literal stillborn god, and the head of a primordial. 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 provides a few suggestions for how they do this, but none of them actually involve killing it. Just dragging it off to hell.
- The Leviathan is on the lower end of the scale, but still pretty horrific. A massive sea creature, one spike big enough to contain an entire temple, made from all the leftover destruction stuff from the creation of the universe.
- The Daelkyr. Extradimensional 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, however, the question is not to ask why Daelkyr look so humanoid, but to ask why humanoids look so Daelkyr...
- Word of God 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've already conquered/subverted almost a continent and would really like to take over the rest...
- While it mostly deals with Gothic horror, the Tabletop Game/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, since their actual nature, methods, and motives are entirely unfathomable. As well, the Nightmare Court could qualify.
- Regular old fiends (demons, etc.) were described in eldritch abomination terms in Van Richten's Guide to Fiends for this setting. It didn't seem inappropriate. 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, stupidly 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 other 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 almighty artifact around which he built his empire is merely a scale said dragon lost. No attempts to stat the dragons have been made as of fall 2017.