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"Mind flayers might comprise the single most dangerous threat to the dominion of humanoids in the daylight lands of the surface world."
— Lords of Madness, page 4

The illithid, commonly known as the mind flayer, is an aberrant humanoid best recognized by its tentacled mouth, which it uses to suck out and consume humanoid brains. It is highly intelligent, and feared for its powerful psionic ability.


A mind flayer stands around the same height as a human, typically between 5'4" and 6'2", having humanoid shape and narrow build. Its head resembles an octopus, with four writhing tentacles where its mouth is. Its skin color ranges from mauve to a greenish lavender, soft and damp like an amphibious creature, and constantly covered by a layer of glistening slime.[1]

A mind flayer's hands have three narrow reddened fingers and a thumb, while its feet have two webbed toes. Its fingers and toes are capped with sharp nails, although despite appearances these are made from soft cartilage and do not serve well as weapons. Its eyes are pure white.

The mind flayer's most deadly physical feature is its tentacled mouth. A mind flayer's four prehensile tentacles can be extended from around 2 feet to to around 4 feet in length, and the mind flayer can manipulate them with great precision. Its small, circular mouth is lined with rows of teeth.[1] It constantly drips an oily slime. Despite lacking a jaw, the mind flayer is capable of speech.[2]

Mind flayers are typically dressed in the dark and menacing fashions of the Underdark. Black robes are common, with tall neck frills, and sometimes adorned with skulls, armored plates, or cloaks sewn no doubt from the hide of some subterranean creature.

They often carry protective magic items, and may wear pieces of armor. Some will wear a unique illithid dampsuit, a moist leather bodysuit intended to protect the mind flayer from deadly heat and dry conditions.


Mind flayers are infamously cruel, insidious, and evil. They have no understanding of the feelings humans call "happiness" or "love", possessed internally of only mankind's negative emotions; particularly contempt, fear, envy and hatred. Frustration is a common illithid emotion.

Despite this, they retain a facade of quiet calmness, and rarely show their true feelings. Their primary motivations include pride, curiosity, and satisfaction.[1] They utterly lack an understanding of human notions such as friendship, honor, loyalty, self-sacrifice, or altruism.

Illithids are highly intelligent, and infamously sadistic. While mind flayers will collaborate with each other when necessary, an individual is entirely self-serving and will happily abandon its allies to save its own life.[2]

Abilities and traits



A mind flayer is vulnerable to certain unique mental and physical illnesses. Exhausting one's mental reserves of psionic energy on a regular basis can cause a brain damage known as psionic cascade, which can trigger psionic powers randomly and eventually cause death. Illithid can also suffer from psychic flareback, a rare backfire which can destroy their ability to use psionic power entirely.[3]

They can contract a common illness called "the ashen", a flu-like disease which causes beige, dry skin and impaired mental functioning. A more serious condition is that of a partial personality, where a remnant of the host body's mind survives the transformation process.[3]



A mind flayer's internal anatomy is functionally very similar to a human, though the organs differ somewhat in appearance. Its nervous system is extremely well-developed, with all of its organs connected directly to the brain.

The mind flayer is warm-blooded.


Mind flayers typically inhabit hidden and underground places, including the Underdark. They detest sunlight, and to be bathed in sunlight is as horrific a concept to the illithid as a human being bathed in blood.

Life cycle

Mind flayers begin their lives as tiny parasitic tadpoles which hatch from eggs in spawning pools. Adult mind flayers are hermaphroditic, and perhaps two or three times in their lifetime they will lay a batch of around one thousand eggs in the pool.

These eggs hatch after around a month and take ten years to reach maturity, by which stage they reach three inches in length. During this time, they are routinely fed a slurry of brain matter and organs.

Over 99% of tadpoles do not reach maturity, instead consumed as psychic fodder by the elder brain, who inhabits the pool. The surviving parastic tadpoles are inserted into the body of a humanoid captured for this purpose, which burrows its way into the individual's brain, growing over the course of one week until it completely replaces the victim's brain.

This transformation process is known as ceremorphosis. Humans are typical victims, but humanoids of similar size are also used, such as elves (including drow), gith, orcs and goblinoids. The resulting mind flayers spend the next twenty years in a period of growth and education before they are permitted to leave the city.[1]

Mind flayers live up to 135 years.

When a mind flayer dies, their brain is ceremonially removed and cast into the spawning pool, where it is absorbed by the elder brain, a enormous and ancient psionic being who rules a mind flayer city. The elder brain absorbs the mind flayer's knowledge. It is the greatest punishment in mind flayer society to be denied joining with the elder brain upon death.


A mind flayer must consume humanoid brains to survive. Its digestive tract is self-aware and absorbs not just the necessary enzymes and hormones, which the mind flayer's parasitic brain is inacapable of producing itself, but the psychic energy of its victims' brains. The mind flayer's mouth produces an enzyme which breaks through the victim's skull, and cannot be stopped by any known substance other than the slime which coats a mind flayer's skin.

A mind flayer must eat one fresh brain per month to survive, or at least one every two weeks for optimal health. Ideally, a mind flayer will eat as many as one brain per week. While the mind flayers breed slaves, these mature too slowly and the dull and the psychic energy of a wretched slave makes for a boring meal.

Surface raids are a preferable source of fresh brains. Intelligent surface-dwelling creatures make preferable meals. Such raids have been known to depopulate entire villages. Among their favourites include humans, drow, halflings and derro. They will occasionally enjoy more exotic fare, including nymphs, umber hulks and xorns.[4]

Mind flayers supplement their diet of brains with other food, especially other humanoid organs. While these lack psychic energy, they do provide the mind flayer with basic nutrients.

Society and culture

Relationships and family

Mind flayers have no concept of friendship or family. Mind flayers deposit thousands of spawn into a communal pool, and do not give any thought to their offspring, most of which will not survive to adulthood.

Communities and settlements

Mind flayers live in well-protected subterranean communities, typically consisting of between 200 and 2,000 individuals. Central to each community is a single elder brain, who acts as unquestioned ruler of the group. Each mind flayer may also own multiple thralls or slaves.[2]

Mind flayer settlements are dimly lit, with their innate darkvision obviating the need for lighting except for their thralls. Vast waterways and fountains serve to maintain high humidity that is amenable to the mind flayers, who prefer to keep their skin moist.[4]

Illithid settlements are designed around a large central plaza. Their architecture is vast and dark, conveying an air of ancient decadence. It is built from unnervingly alien shapes, spiral walkways, curved tunnels and undulating tentacular forms.


Mind flayers frequently operate alone, but they will work in pairs or in larger groups when the situation demands it. A collective of three to five mind flayers assembled for specific purpose is known as an inquisition, and somewhat resembles an adventuring party in purpose and variety of composition.

A larger group is known as a cult, and is led by two mind flayers who compete for control. The mind flayers are usually accompanied by mind-controlled thralls, and as in normal illithid society it is common for the number of thralls to outnumber the mind flayers at least two to one.[2]


Mind flayers are feared and reviled by most sentient races.

The mind flayers truly hate the githyanki and githzerai, who they once kept enslaved thousands of years ago, and the hatred is mutual. They regularly recruit spies within gith society, aiming to keep the two gith factions at war with each other so that they never unite against the mind flayers.

Mind flayers particularly fear the undead, whose unliving minds cannot be detected or harmed with psionics, and who often have no brains for the mind flayer to eat.[4]

Allies and minions

"A lone illithid hunting in its element is more than a match for a group of surface warriors, and seldom is an illithid alone."
— Lords of Madness, page 61

Mind flayers regulary keep humanoids as enslaved thralls, controlled by constant psionic bombardment and bred to be docile. The life of a thrall is nightmarish and short, and usually ends with the mind flayer eating their brains and feeding the rest of the body to other thralls. Mind flayers typically use their thralls as slaves and armies, and owning a large collection of unique slaves carries great social status.

Mind flayers do not form alliances unless they have something to gain.


The most commonly worshiped mind flayer deity is Ilsensine, an illithid deity of knowledge. It has no physical body or gender, but manifests in the form of a giant brain whose ganglia reach to all corners of existence and learn from the minds of all beings across the multiverse.[4]

Illithid clerics of Ilsensine live secluded and monastic lives, and are rarely seen outside of their temples. They spend much of their time in psionic research and the pursuit of esoteric knowledge.

The aphorism "with an illithid's faith" is used by adventurers to mean "with treachery".[5]


The mind flayers are telepathic, and have no need for a spoken language of their own. However, they are capable of using and understanding speech, and typically speak Undercommon.[4]

The mind flayers possess a written script, Qualith, which has no spoken form. It consists of raised dashes and spaces, and is read by touch. It is written in four parallel lines which are intended to be read simultaneously, and is a written interpretation of telepathic communication. It is commonly engraved on walls in illithid cities, but is extremely difficult for non-illithids to comprehend.[4]

Mind flayers are intelligent, and commonly learn other languages, including Common.


Illithid society possess the ability to craft a variety of magic items. Individual mind flayers primarily seek to acquire items which improve their defensive ability or enhance their intellect.[1]

Mind flayer societies have no use for coinage. The elder brain maintains a perfect record of all transactions which take place within its community, so that currency is only used for trading with outsiders, such as surface-dwellers or drow cities.[4]



The origins of the mind flayers are shrouded in mystery. Cryptic fragments of information on their origin appear in such ancient texts as the Sargonne Prophecies. They appear in the mythology of the most ancient races, and pre-date written history.[6]

The beings who created the mind flayers are unknown. According to an ancient text known as The Astromundi Chronicles, the mind flayers so hated their creators that they destroyed them and erased all evidence of their existence from history.[4] This account is dismissed by numerous scholars, who note its similarity to the history of the githyanki and githzerai.[6]

One theory posits that the illithid derive from the Far Realm, an alien place beyond the edge of time whose influence warps reality into abberant forms of life. Some suggest that they were not native to there, but merely came to our reality from that place.

Today, even the ancient elder brains do not remember how their species once rose to power.

In the view of D&D designer Mike Mearls, in the 2017 video Mind Flayers in Dungeons & Dragons, the mind flayers are essentially a biological constructed servitor race who serve the elder brains.

Empire of the illithid

"Boundless, illithid influence enfolded worlds without number."
— The Planetreader's Primer

It is widely accepted that illithid once ruled a truly massive empire, spanning countless worlds and dwarfing any human civilization known today. Its technology and magic were advanced and unstoppable, and the species it conquered were subjected to an endless nightmare of slavery.

The illithid empire ruled in perpetuity, until the stars burned out and the very worlds around them grew cold. Then, at the end of time, the mind flayers finally faced an unstoppable adversary. No records remain of who or what this was; only that the illithid empire slowly but surely crumbled in its wake.[4]

In an insane solution, the few surviving illithid of sacrificed countless elder brains, the psionic leaders of their race, hoping to tear a psychic rift in the universe and overcome the laws of time itself. The resulting psychic maelstrom cast the illithid back in time, where they could patiently begin their conquest anew.[4]

Ancient history

Millennia ago, the empire of the illithid slowly began to establish itself for a second time, and quickly succeeded in enslaving the species known as the gith. Unfortunately, the mind flayers were overconfident, and failed to notice when the gith began to evolve resistance to their psionic control.

Some two thousand years ago, the gith rose in rebellion against their masters and overthrew, destroying the second illithid civilization and scattering them across worlds. Much of the illithid futuristic technology and magic was lost or destroyed.[4]

Following the rebellion, the gith soon began fighting amongst themselves. They divided themselves into two subspecies: the contemplative githzerai, who retreated to the chaotic plane of Limbo; and the warlike githyanki, who established fortresses in the Astral Plane.

The mind flayers established themselves in hidden and underground places, particularly the Underdark, where they need not fear sunlight or the encroachment of the surface peoples.

Recent history

The hidden settlements of mind flayers routinely prey on humanoid creatures, who they capture alive as a food source and to use as slaves. They are also known to interfere with politics on the surface world, influencing rulers peoples with psychic control and propaganda.

The illithid believe it is their fate to rule the multiverse, in an impossibly distant future when the suns of worlds have faded and the mind flayers may freely walk on the surface. The dream of mind flayers on many worlds is to extinguish the sun, but this is generally considered impractical.

Notable mind flayers

For a full list of mind flayers, see Category:Mind flayers.

Related creatures

Unusual hosts

Mind flayers are usually created by introducing a parasitic illithid tadpole to a human or similar humanoid. In some cases, rare and unique creatures have been created by introducing a tadpole to an unusual creature.

The urophion is an illithid roper. Despite having an intellect equal to any normal mind flayer, they hold low status in illithid society, and spend their entire lives as guards.

An illithid tadpole unintentionally allowed to grow without being implanted into a host can grow until it becomes a neothelid, a wild psionic predator. They are typically formed from tadpoles who survive the destruction of an elder brain, who soon turn on each other in a cannibalistic frenzy until only one massive survivor remains.

Variant mind flayers

In rare occasion, a powerful and supremely intelligent mind flayer known as an ulitharid is spawned. They are some eight or nine feet tall, with six-tentacled mouth. Fewer than 1% of mind flayers are ulitharids, and they always rise to the highest status in their community, below only the elder brain. Many communities lack even a single ulitharid.

A mind flayer who becomes a lich is known as an alhoon, or colloquially the illithilich. They no longer need to eat brains to survive, but suffer from horrendous skin dessication, requiring them to frequently bathe in liquid and consume soup.

The mind flayer vampire is cursed with both the need to drink blood and consume brains. A mind flayer afflicted with vampirism inevitably turns feral.


Mind flayer settlements are often inhabited by aberrant creatures believed to originate from the original long-lost mind flayer homeworld, where they once filled an ecological niche similar to animals. Like the mind flayers, they possess psionic ability and monstrous appearance.

The large, predatory embrac is noted for its eight poisonous tentacles, with which it can grapple opponents. The kigrid resembles a large monstrous clawed cat. The small saltor is a baboonlike furred scavenger with the ability to craft and wield rudimentary weapons and speak basic language.[7]


The elder brain is a massive communal brain formed from the minds of dead mind flayers. They occasionally produce a brain golem.

Publication history

Original D&D

The mind flayer first appeared in Strategic Review issue #1 (Spring 1975). It is described as "a super-intelligent man-shaped creature with four tentacles by its mouth", which are used to penetrate the skull and draw out the brain. They possess a mind blast which is more powerful against opponents with lower Intelligence scores, and have 90% magic resistance.

They later appeared in Eldritch Wizardry (1976), p.39, where they are said to have their own spoken language.

Basic D&D

AD&D 1st edition

The mind flayer appears in the Monster Manual (1e) (1977), p.70. Artwork establishes what would become the creature's iconic appearance, wearing long wizardlike robes with tall collars and adorned with skulls. Here they are described as subterranean, as they detest sunlight, and inhabiting a rumored city beneath the earth.

AD&D 2nd edition

The mind flayer appeared in Monstrous Compendium Volume One (1989). The lore behind the mind flayer is expanded here. They live in underground communities of between 200 and 2,000 plus at least two slaves per mind flayer.

The Illithiad (1998), a lore-heavy supplement for AD&D 2nd edition released toward the end of that edition after TSR's bankruptcy and acquisition by Wizards of the Coast, is a 96-page supplement dedicated entirely to the mind flayer.

D&D 3rd edition

The mind flayer appears in the Monster Manual (3.0) (2000) and Monster Manual (3.5) (2003), p.186-188. Mechanically, they must now attach all four tentacles to draw out the brain, unlike in AD&D 2e and earlier where a single tentacle can drill its way to the brain.

The best sourcebook detailing the mind flayers is Lords of Madness (2005), which dedicates an entire chapter to describing illithid anatomy and society.

As one of the creatures considered unique Product Identity by Wizards of the Coast, the mind flayer does not appear in the System Reference Documents.

D&D 4th edition

The mind flayer appears in the Monster Manual (4e) (2008), p.188-189, which depicts the mind flayer infiltrator, a level 14 lurker, and the mind flayer mastermind, a level 18 elite controller. They are described as encountered alongside with drow, driders and grimlocks.

Further mind flayer lore is detailed in Monster Manual 3 (4e) (2010), p.136-139, which details the mind flayer inquisitor, mind flayer scourge, the thoon hulk, and the level 23 elite controller elder brain.

D&D 5th edition

The mind flayer is detailed in the Monster Manual (5e) (2014), p.221-222.

Creative origins

The Burrowers Beneath (1975), which inspired the mind flayer

The mind flayer was an original invention of D&D creator Gary Gygax. The creature's tentacled mouth was inspired by the cover art of Lovecraftian Burrowers Beneath (1975). In an ENWorld forum Q&A, Gygax recounts:[8]

"As one that enjoys the whole plethora of Lovecraftian yarns, those written by HPL and those created by his cadre of followers, I freely admit that the cover of Brian Lumely's paperback novel, The Burrowers Beneath, inspired me to create the D&D mind-flayer. I hoped then that it would have been a monstrous creature that Lovecraft himself would have approved of :D"

Gygax's goal was to create an original race who preyed upon humans for sustenance.

Charles Stross, inventor of the githanki and githzerai, speculated that the mind flayer may have been influenced by the works of science fiction author Larry Niven, whose works include a race of telepathic slavers called the Thrint. However, in an ENWorld Q&A thread, Gygax described that there was no connection:[9]

"No need to speculate, for I can set forth the process in a few words. Larry Niven's writing had nothing to do with the creation of the Illithid race for the AD&D game."

Reception and influence

Video game appearances

The mind flayer is one of the oldest D&D creatures considered product identity, a unique creation of D&D where copyright is currently reserved by Wizards of the Coast and does not appear in the System Reference Documents.

Despite this, the mind flayer or similar creatures have appeared in several computer roleplaying games. Notable examples include:

  • The open source roguelike NetHack, where the mind flayer and master mind flayer possess a brain attack which causes players to forget previously identified items and level layouts. Eating a mind flayer corpse can bestow the player character with intrinsic telepathy.
  • The Japanese Final Fantasy RPG series (1987 to current), where the mind flayer has made numerous appearances. They have a squid-like appearance, and due to inconsistent translations are given various names including Mindflayer, Mind Flare and Sorcerer.
  • Cult classic action RPG Demon's Souls (2009), where mind flayers guard the Tower of Latria.
  • Baldur's Gate III features the mind flayer in a prominent role.

Further reading

The most highly detailed resources on the mind flayer are The Illithiad (1998), a 96-page supplement for AD&D 2nd edition; and Lords of Madness (2005), which dedicates an entire chapter to that species.


  1. 1.0 1.1 1.2 1.3 1.4 Lords of Madness (2005), p.61-67.
  2. 2.0 2.1 2.2 2.3 Monster Manual (3.5) (2003), p.186-188.
  3. 3.0 3.1 The Illithiad (1998), p.33-35.
  4. 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 Lords of Madness (2005), p.70-88.
  5. SJR6 Greyspace (2e) (1992), p.69.
  6. 6.0 6.1 The Illithiad (1998), p.36-41.
  7. Lords of Madness (2005), p.154.
  8. Q&A with Gary Gygax, page 408. ENWorld, Sep 15, 2007.
  9. Q&A with Gary Gygax, page 235. ENWorld, Sep 22, 2005.