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Greyhawk creature
A typical illithid, as depicted in the Monster Manual (2003).
Alignment Lawful Evil
Type Aberration
First appearance The Strategic Review #1 (Spring 1975)

Illithids (commonly known as mind flayers) are monstrous, humanoid aberrations with psionic powers. They live in the moist caverns and cities of the enormous Underdark. Illithids believe themselves to be the dominant species of the multiverse and use other intelligent creatures as thralls, slaves, and chattel.


Illithids spend much of their time in intense study and experimentation, gathering knowledge of all sorts that will enable them to eventually reconquer the universe and hold it for good. They frequently meddle in the politics of other races through subtle psychic manipulation of key figures, not to cause chaos but so as to better understand the dynamics of civilization. They regularly probe the minds of surface dwellers so as to gather intelligence and learn about new advances in magic and technology. Illithids also do a good deal of research themselves, mainly focused on developing new psychic powers.

Illithids regularly conduct raids on all sentient settlements to acquire new thralls, because their existing stock of sentient thralls do not breed fast enough to satisfy their food and labor needs. Typically, a group of mind flayers will teleport to the settlement and swiftly incapacitate them with their psychic powers. The captives will then be marched all the way to the illithids' underground settlement by specially trained and conditioned thralls. Great care is taken to cover their tracks.


Illithids typically dwell in dim, underground settlements, usually in the Underdark. Perhaps the best-known illithid settlement on Oerth is the city of Dra-Mur-Shou, located within several miles of the Vault of the Drow. A number of illithids also make their home in the drow city of Erelhei-Cinlu, due to the presence of a well-known mind flayer research center known as the Antisolar Institute.

Illithids also have a strong presence in Greyspace and spheres beyond. The primary spelljamming ship used by illithids is the nautiloid, a 35-ton craft resembling a nautilus. Nautiloids are 125' to 180' long, including the tentacle-like piercing ram. The ship's coiled shell provides the comfort of enclosed space and protects the illithids from the rays of solar bodies. Less common illithid vessels such as the 25-ton squid ship, the 70-ton octopus, and the 100-ton cuttle command also resemble the cephalopods after which they are named.

In Greyspace, the largest illithid settlements are the city of Sharpbeak on Celene and the settlement of Skullbringer in the Grinder. Worlds ruled by illithids in other spheres include Falx, Ssirik Akuar, Penumbra, and Glyth. The fortress of Yuhnmoag is located on the Paraelemental Plane of Ooze.

Typical physical characteristics

Illithids have humanoid bodies, with octopoid heads. They have four tentacles around a lamprey-like mouth, and require the brains of sentient creatures as part of their diet. An illithid who snares a living creature in all four of its tentacles can extract and devour its living brain. Illithid eyes are pale white, and though their vision is limited to roughly 60 feet, they can see perfectly well in both darkness and light. Their sense of hearing is slightly poorer than a human's; they have difficulty distinguishing between several sounds mixed together. Their skin is mauve and covered in mucus, and is very sensitive to sunlight; illithids who make extended forays to the surface must wear protective clothing to maintain their skin moisture.

Among the most feared illithid abilities is the dreaded mind blast, where the creature emits a cone-shaped psionic shockwave with its mind in order to incapacitate any creature for a short amount of time. Illithids also have other psionic powers, generally telepathic in nature, although their exact effects have varied over editions. Other powers include a defensive psionic shield and powers of psionic domination for controlling the minds of others.


Illithids are hermaphroditic creatures who each spawn a mass of larvae twice in their life. The larvae resemble miniature illithid heads or four-tentacled tadpoles. Larvae are left to develop in the pool of the elder brain. The ones that survive after 10 years are inserted into the brain of a sapient creature. Hosts are determined in a very specific manner. Hosts generally are humanoid creatures that are between 5 feet 4 inches and 6 feet 2 inches tall. The most desired races for hosts are humans, drow, surface elves, githzerai, githyanki, grimlocks, gnolls, goblinoids, and orcs. Upon being implanted, the larva then grows and consumes the host's brain, absorbing the host's physical form entirely and becoming sapient itself, a mature (but still young) illithid. This process is called ceremorphosis. Illithids often experiment with non-humanoid hosts, but ceremorphosis involving other creatures usually fails, killing both host and larva.

Occasionally, ceremorphosis can partially fail. Sometimes the larva does not contain enough chemicals to complete the mutation, sometimes there is psionic interference. Whatever the reason, it has happened that ceremorphosis has ended after the internal restructuring, resulting in a human body with an illithid's brain, personality and digestive tract. These unfortunates must still consume brains, typically by cutting open heads (as they lack the requisite tentacles). These beings are often used as spies, where they easily blend in with their respective host types.


Illithids are usually lawful evil.


An illithid city is ruled by a creature called an elder brain which lives in a pool of cerebral fluid in the city's center. When an illithid dies, its brain is extracted and taken to the pool. Illithids believe that when they die their personality is incorporated into the elder brain, but this is not the case. When the brain of an illithid is added to the elder brain, the memories, thoughts and experiences are consumed and added to the sum of the whole, but all else is lost. This fact is a closely guarded secret of the elder brains, since all illithid aspire to a form of immortality through this merging process. An extremely ancient elder brain is called a god brain, because its psionic powers are almost limitless.

Since the elder brain contains the essence of every illithid that died in its community, it functions in part as a vast library of knowledge that a mind flayer can call upon via telepathy. The elder brain in turn can communicate telepathically with anyone in its community, issuing orders and ensuring everyone conforms.

Illithids generally frown upon magic, preferring their natural psionic ability. Psionic potential is an integral part of the illithid identity, and the elder brain cannot absorb the magical powers of an illithid mage when it dies. They tolerate a limited study of wizardry, if only to better understand the powers employed by their enemies. However, an illithid who goes too far and neglects his psionic development in favor of wizardry risks becoming an outcast. Denied the possibility of ever merging with the elder brain, such outcasts often seek their own immortality through undeath, becoming illithis liches called alhoons.


Illithids revere a perverse deity named Ilsensine, and once had a second deity named Maanzecorian. A few are attracted to the veneration of Mammon, archdevil of greed.


Illithids typically communicate through psychic means. They project thoughts and feelings to each other in a way non-illithids can scarcely comprehend. When they do feel the need to write, illithids do so in qualith. Instead of typical alphabet-based writing, illithids write in qualith by making marks consisting of four broken lines. They use each tentacle to feel the breaks in the lines, making it basically similar to braille. However, qualith is extremely complex, as each line modifies the preceding lines through explaining abstract concepts associated with the above words in ways no human can understand; only by understanding all four lines simultaneously can the meaning be understood properly.


The origins of the illithids are often shrouded in mystery, with conflicting stories offered in various D&D products, in past editions and in the current version of the game. These different versions can be taken as successive retcons or simply different stories hiding the true nature of the illithids, which may be something else entirely.

The 3rd Edition D&D book Lords of Madness states that illithids are refugees from a far distant future. Facing extinction at the hands of some unknown adversary, they sacrificed a large number of elder brains to generate a temporal rift that transported the survivors aeons into the past, but little more than a mere two thousand years before the present.

The 2nd Edition book The Illithiad suggests they may be from the Far Realm, an incomprehensible plane completely alien to the known multiverse. There is no mention of time travel in this theory, although it is mentioned that time travel may be one of the ways of reaching the Far Realm. The illithids emerged somewhere and somewhen countless thousands of years ago, beyond the histories of many mortal races, and spread from one world to another, and another, and so on. It is explicitly stated in this book that the illithids appear in some of the most ancient histories of the most ancient races, even those that have no mention of other races.

The 4th Edition preview Wizards Presents Worlds and Monsters once again has mind flayers originating from the Far Realm.

In these two differing versions of the story, much of the variance hinges upon a fictional text called The Sargonne Prophecies. The Illithiad described the Prophecies as misnamed, and that much of it sounds more like ancient myth than prophecy. Lords of Madness takes the name more literally, and states that The Sargonne Prophecies are in fact prophecy — or, perhaps more accurately, a history of the future.

Yet another version of illithid origins comes from The Astromundi Cluster, a Spelljammer boxed set produced before The Illithiad. This version holds that the illithids are descended from the outcasts of an ancient human society that ruled the now-shattered world called Astromundi. The outcast humans eventually mutated, deep underground, into the mind flayers. This boxed set also introduced the entity known as Lugribossk, who was depicted as a god of the Astromundi flayers then, but was later retconned into a proxy of the god Ilsensine. In the retconned history of the illithids found in either The Illithiad or Lords of Madness, the emergence of illithids in Astromundi becomes a freak occurrence due to the intervention of Ilsensine through its proxy, since the illithids of Astromundi have their own histories as emerging solely upon that world.

However and whenever it occurred, when the illithids arrived in the Material Plane of the far past, they immediately began to build an empire by enslaving many sentient creatures. They were very successful, and soon their worlds-spanning empire became the largest one the multiverse had ever seen. They had the power — in terms of psychic potency and the manpower of countless slaves — to fashion artificial worlds. One such world was this empire's capital, called Penumbra, a diskworld built around a star, which was a thousand years in the making. Such was their might that the Blood War paused as the demons and devils considered a truce to deal with the illithid empire.

Eventually, the primary slave race of the illithids developed resistance to the mental powers of their masters, and revolted. Led by the warrior Gith, the rebellion spread to all the illithids' worlds, and the empire collapsed. The illithid race itself seemed doomed.

Fortunately for the illithids, Gith was betrayed by one of her own generals, Zerthimon, who believed she had grown tyrannical and over-aggressive. Civil war erupted, and the race factionalized into the githyanki and the githzerai. This disruption allowed the illithids to retreat to underground strongholds where they still dwell.

Dungeon Magazine #100 claims the original home of the gith forerunners was a world known as Pharagos. Currently it is described as, "an unremarkable Material-Plane world, a far cry from the hotbed of magical activity and divine intervention that is the Forgotten Realms campaign or the World of Greyhawk." Beneath the Wasting Desert on that world, however, is the petrified corpse of the long-dead patron deity of the ancestors of the gith races. As is recounted in most 1st and 2nd edition sources, the ancestors of the gith forerunners were a human civilization before being modified by countless generations of illithid breeding and profane science.

The background material of the Chainmail game places the gith forerunners in a subterranean empire called Zarum in Western Oerik, where they dominated many other races from their capital city of Anithor. These gith seem to have been divided into a rigid caste system, their lives ruled by ancient ritual. The ruins of Zarum overflow with sacred spaces and temples, though the names of the ancient gith gods are unknown today. The period of Zarum's height is not entirely clear, but grey elf sages speculate it was approximately 2,000 years before the Demon Wars that ravaged Western Oerik, or 3,000 years before the present.

At some point, the illithids invaded Zarum from a neighboring plane of existence. Though the gith fought fiercely, they were no match for the psionic might of the mind flayers, and soon they were enslaved. The River of Angry Souls is a remnant of one of the terrible battles between the illithids and the soon-to-be enslaved gith. Many were brought to the Outer Planes and elsewhere to serve as illithid slaves. Other cities in Zarum were transformed into work pits where illithid overseers forced their slaves to toil for countless generations.

After Gith's rebellion, she led her people to the Astral Plane. While a few subject races and surviving illithids remained on Oerth, the gith forerunners have departed the world, seemingly for good. If they retain any interest in the ruins of Zarum, it is well concealed. A portion of the ruins of Anithor were eventually colonized by the drow of House Kilsek, who named their new settlement Kalan-G'eld.


When an illithid undergoes ceremorphosis, it can occasionally take on some elements of the absorbed host creature's former mind, such as mannerisms. This typically manifests as a nervous habit and/or reaction, like nail-biting or tapping one's foot. An adult illithid has even been known to hum a tune that its host knew in life. When a mind flayer inherits such a trait, it usually keeps it a closely guarded secret; were its peers to learn of such a trait, the illithid in question would surely be killed. This is due to an illithid legend of a being called the "Adversary." The legend holds that an illithid larva that undergoes ceremorphosis will eventually take on the host's personality and memory in its entirety. This "Adversary" would, mind and soul, still be the host, but with all the inherent abilities of an illithid.

In the 2nd Edition AD&D adventure Dawn of the Overmind, author Bruce Cordell revealed the nature of the Adversary. This being was an illithid created from the host body of a man named Strom Wakeman, a character referenced in some of Cordell's other 2nd Edition works, most notably as the "author" of The Illithiad supplement.

Wakeman, an enterprising trader and scholar of Underdark exotica, allowed himself to be captured by the illithids on one of his expeditions. Through the use of a non-magical mixture of various herbs that Wakeman named laethen, he was able to preserve his consciousness through ceremorphosis, and learned to use his psionic powers to keep from having to consume brains. Thus he worked against the illithid plots from within. The legend of the Adversary was born from his frequent sabotage, though the actual acts were never connected to him. The players' characters in the adventure become his agents in stopping the illithids' plans, as his own movements rely upon secrecy from his "fellow" illithids.

For another person to imitate Wakeman's deed would require at least one dose of laethen (the making of which Wakeman kept secret) and to be put under ceremorphosis within a week of consumption. The drug only has a 40% chance of success, and the new illithid must also never consume a brain, for the act destroys the host's personality and replaces it with the illithid personality.

Illithid variants


A number of illithid variations exist.

  • Alhoon: Alhoons (also called illithiliches) are illithids that have grown powerful enough in magic to become liches. Alhoons are generally pariahs in illithid society because they go against most illithids' eventual goal; to merge with the Elder Brain, both physically and psionically. Alhoons, on the other hand, are more concerned with their own personal survival.
  • Ulitharid: Ulitharids are created from tadpoles much like standard illithids; fewer than 1% become ulitharids, and it is impossible to determine whether a tadpole will become an ulitharid until ceremorphosis is complete. Superior in nearly all ways to a regular mind flayer, ulitharids possess two extra tentacles, which are twice as long as the others, and an extreme arrogance, even by the standards of their own kind. Only the elder brain holds more sway within an illithid community.
  • Vampiric illithids: The origins of these unique undead mind flayers are unclear. All that is known of these creatures is that they cannot create spawn, need both fresh blood and fresh brains to survive, are more feral than typical illithids, and are barely intelligent.

Related creatures

A number of unusual creatures have been created and bred by illithids, or have evolved from illithid tadpoles.

  • Brain golem: An eight-foot-tall humanoid-shaped construct made entirely of brain tissue, these creations exist only to serve an elder brain and its illithid community.
  • Brainstealer dragon: A mix of illithid and dragon, these powerful wyrms occasionally rule over illithid communities that lack an elder brain.
  • Illithid symbiont: Illithids often create symbionts both for themselves and their slaves. Some are intended to sow fear among their enemies, while others enhance their own offensive and defensive capabilities. Known illithid symbionts include the mnemonicus, wriggler, and carapace symbionts. Carapace symbionts are bred to serve as personal armor and boost other abilities. Known varieties include the backwatcher, fastbreak, hardy, silent, slippery, and strongarm carapaces.
  • Illithidae: Illithidae are to mind flayers as less intelligent animals are to humans. Known types include the cessirid, embrac, kigrid, and saltor. Dragon magazine once published a template for use in creating an illithidae creature, for use with the 1st Edition of the Advanced Dungeons & Dragons game.
  • Illithocyte: Illithid tadpoles that survived the fall of a mind flayer empire, they evolved into a new life form and crawl about in groups seeking psychic radiation on which to feed.
  • Kezreth: A living troop transport and battle platform created from the severed head of a shamed illithid. They serve in this capacity in the hope of redeeming themselves and being allowed to return to the elder brain.
  • Larval flayer: A step between larva and neothelid, these creatures looks like overgrown tadpoles. The existence of these beasts is a guarded secret among illithids, and it is considered impolite to speak of them.
  • Mind worm: Created by illithids to serve as assassins and bounty hunters, these powerful psionic creatures resemble smaller purple worms. They can attack from far distances with their probe worms.
  • Mindwitness: Inserting an illithid tadpole into a beholder results in these abominations, which are used as guards and sentries.
  • Mozgriken: An illithid tadpole inserted into a svirfneblin while subjected to a dangerous psionic ritual creates a mozgriken. These three-tentacled ceremorphs are despised by all, but their aptitude for stealth and psionic power of shape control makes them useful spies for the illithids.
  • Neothelid: If an illithid tadpole fails to undergo ceremorphosis, it may eventually grow into a neothelid, an incredibly powerful worm-like creature with illithid tentacles at the forefront of its body and immense mental powers.
  • Nerve swimmers: Derived from immature illithid tadpoles, these entities are living instruments of torture and interrogation.
  • Nyraala golem: A flailing, slimy, tentacled construct capable of launching surprise attacks. They often serve as guards, and are prized because their creation does not involve petitioning the elder brain to surrender part of its mass.
  • Octopin: A six-tentacled, purple-skinned monstrosity with a single eye created by mind flayers.
  • Oortling: These docile humanoids with enlarged brains are bred as food by spelljamming illithids.
  • Tzakandi: Illithid tadpoles inserted into lizardfolk create tzakandi, which the mind flayers use as slave laborers and personal guards.
  • Uchuulon: A chuul implanted with an illithid tadpole becomes an uchuulon. Also known as slime chuuls, illithids use them as hunters and guardians.
  • Urophion: Inserting an illithid tadpole into a roper results in these miserable creatures, which are used as guards and sentries.
  • Ustilagor: Mind flayers farm these larval intellect devourers for food and sentries.
  • Vampire squid: Servitor creatures created by illithids to extend their reach below the surface of Underdark waters. They have a maw of sharp teeth which can be turned inside out and function as defensive spikes (see Dragon #227).
  • Voidmind creature: A voidmind creature is an ordinary creature (such as a normal humanoid, animal, etcetera) whose mind has been nearly completely devoured by a mind flayer, but enough has been left intact for basic motor function. Further psionic rituals give these near-dead creatures a semblance of life. The resulting creatures act as minions and spies for the illithids.

Creative origins

Mind flayers was created by Gary Gygax, who has said that one of his inspirations for them was the cover painting of the book The Burrowers Beneath by Brian Lumley.[1]

Publishing history

Illithids first appeared in The Strategic Review #1 (Spring 1975). They were also included in the Eldritch Wizardry supplement for the original Dungeons and Dragons game (1976), wherein they are described as "super-intelligent, man-shaped creatures of great (and lawful) evil, with tentacles that penetrate to the brain and draw it forth for food."

In 1977, the mind flayer appeared in the first edition Monster Manual, in which it is described as an "evil subterranean creature that considers humanity as cattle to feed upon, and draws forth brains with its tentacles." In 1983, Roger E. Moore authored "The Ecology of the Mind Flayer," which was featured in Dragon #78.

The article "The Sunset World," by Stephen Inniss in Dragon #150 (October 1989) presented a world that had been completely ravaged by mind flayers. The "Dragon's Bestiary" column, in the same issue and by the same author, described the illithidae, the strange inhabitants of this world.

The mind flayer made its first second edition AD&D appearance in the Monstrous Compendium Volume One (1989), which was reprinted in the Monstrous Manual (1993).

The 'ulitharid, or "noble illithid" was introduced in the Dungeon adventure "Thunder Under Needlespire" by James Jacobs in Dungeon #24 (July/August 1990), and was later included in the Monstrous Compendium Annual One (1994).

The Complete Psionics Handbook (1991) presented ways on using mind flayers with psionic powers.

The alhoon was introduced in the Menzoberranzan boxed set (1992).

The Illithiad (1998), and the Monstrous Arcana module series that accompanies it, greatly developed the mind flayer further. The Illithiad introduced the illithid elder brain and the urophion. The module Dawn of the Overmind featured an origin story for the illithids.

The mind flayer made its third edition debut in the Monster Manual (2000). The illithid was classified as "Product Identity" by Wizards of the Coast at this time and was not released under its Open Game License.

Savage Species (2003) presented the mind flayer as both a race and a playable class. In 2003, the mind flayer appeared in the revised Monster Manual for edition 3.5. The mind flayer received its own chapter in Lords of Madness (2005). The Expanded Psionics Handbook (2004) re-introduced the psionic mind flayer. Monster Manual V (2007) introduced the illithids of Thoon and the concept of "quintessence," a commodity valuable to that group of illithids.

In 2008, the mind flayer was updated for 4th edition in the Monster Manual (2008).

In 2014, the mind flayer was updated for 5th edition in the Monster Manual (2014).


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  • Baker, Rich, James Jacobs, and Steve Winter. Lords of Madness. Renton, WA: Wizards of the Coast, 2005.
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  • Pramas, Chris. "Exiles from the Vault." Dragon #298. Renton, WA: Wizards of the Coast, 2002.
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  • -----. Monster Manual: Core Rulebook III v.3.5. Renton, WA: Wizards of the Coast, 2003.
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