"It is absolutely necessary, for the peace and safety of mankind, that some of earth’s dark, dead corners and unplumbed depths be let alone; lest sleeping abnormalities wake to resurgent life, and blasphemously surviving nightmares squirm and splash out of their black lairs to newer and wider conquests."

-- H.P. Lovecraft, At the Mountains of Madness

A drow runs screaming out of a newly discovered cavern, muttering incomprehenisble fears under his breath. Four twitching, mauve tentacles turn the pages of a book as delicately as fingers would hold a flower. A village is found littered with the corpses of its inhabitants, each one with its skull cracked open and left empty to the summer air.

Remnants of Ancient Days

While most denizens of the Material Plane know illithids as mind flayers, psionic horrors from the Underdark, the pockets of illithids there are in fact the last survivors of a terrible and ancient war.

While some sages believe the illithids originally came from the Far Realm, the earliest history of their race began in the Astral Plane. Using interplanar ships called nautiloids, they traveled and conquered across the multiverse.

That all disappeared in just one year, when the enslaved gith rose up in rebellion, a mass genocide that missed only a few small colonies in the Underdark. Their empire gone, the illithids wait and plot in the darkness, dreaming of reclaiming their rightful place as rulers of the multiverse.

Food for Thought

Whatever their true origins, illithid biology is vastly different from most races. Their signature cephalopod-like heads and vibrant skin are enough to trigger the distrust of most other peoples, but the reason they are hated is their diet: the brains of sentient creatures.

While they are capable of eating other foods, and many do, they tend to grow weary and lethargic if they do not eat at least one brain every few weeks, giving rise to the nickname "mind flayers."

Body Snatchers

Illithids are not born like most other races. Instead, they lay eggs that hatch into small, tadpole-like creatures. When introduced to the body of a sentient humanoid, the tadpole latches onto the brain, feeding off it to grow. The host is alive throughout this process, and may even be unaware of the parasite. Eventually, through a process called ceremorphosis, the tadpole grows large enough to begin replacing the brain's functions, ultimately attaching itself to the brain stem and taking over the body.

Once in control, the host enters a coma-like state and begins to undergo massive changes to accomodate the parasite. The host's skin becomes thinner and slimy, changing color. All of its hair falls out, as do its teeth. Finally, the nose forks and grows rapidly, becoming four feeding tentacles.

As a result, each illithid has varying biology depending on the original host, and may even retain scraps of the host's memories or personality. A dwarf-based illithid might be shorter and stubborn, and a tiefling-based one might retain its horns or tail and unease around strangers.

Separated from the Hive

In most illithid societies, each individual retains a psychic link to an elder brain, an ancient creature that resembles a tentacled brain. Each colony has one elder brain that directs its connected illithids much as a queen bee directs its drones. However, each illithid retains some level of individuality, and some ultimately seek to escape from the elder brain's control to seek their own ambitions.

It is not easy to plan an escape when your warden can read your thoughts, and few illithid separatists survive to make it to the surface. However, those that do usually end up as adventurers, since few cities will accept them without proof of their goodwill.

Illithid Names

Accustomed to telepathic communication, most illithids identify themselves using complex psychic signatures. However, many find that taking a verbal name helps when interacting with other peoples, and so create names that are rough approximations of their telepathic signatures.

Although technically sexless, most illithids identify themselves as the gender of their original host. However, some identify differently, and some prefer neutral pronouns.

Illithid Names: Aurangaul, Birazi, Cephalossk, Drukt, Drusiss, Egrulan, Kuphull, Lugribossk, Quoor, Ralayan, Sardsult, S'venchen, Tharcereli, Tobulux, Zellix

Qualith

Qualith is a system of tactile writing (similar to braille) that is read by an illithid's tentacles. Qualith is written in four-line stanzas and is so alien in construction that non-illithids must resort to magic to discern its meaning. Though Qualith can be used to keep records, illithids most often use it to mark portals or other surfaces with warnings or instructions. As adventurers, many find little use for it other than keeping notes for themselves.

Illithid Quirks