Ceremorphosis

Mind Flayers reproduce through spawning psionically charged tadpoles, which are implanted into the brains of other races, transforming them via a psychometabolic process known as ceremorphosis.
In most humanoid species this results in the birth of a new Mind Flayer, but other species (by way or natural law, or via intentional intervention) provide widely varying results. This has resulted in the array of ceremorphs throughout wildspace anf the astral sea.

Mind Flayer, aka Illithid

The most common example of the genetic lineage seen across the known multiverse is the Ceremorph, Illithid. Detailed heavily elsewhere, of note in this guide is the moral flexibility of the species in wildspace, particularly in dealing with other species, communities, and organisations. While many Illithids prey upon space lanes and maintain plans for multiversal domination, select groups and individuals are anywhere from neutral to genuine allies of the free folk of space. These are the exception, however, not the rule, and travellers are advised to tread with caution.
Mind Flayers includes the subspecies of Ulithiards, magicqlly created Alhoon and Vampiric Illithids, and the Elder Brains formed from the remains of deceased Illithids.

Illithid Ceremorph Fleet, (ICF)

The largest known organisation of Mind Flayers across the multiverse is the Illithid Ceremorph Fleet. They have a presence of some type in most populated systems, and several hidden bases within the astral sea. For more details, see the article Illithid Ceremorph Fleet.
The ICF is splintered into location based heirarchies, typically lead by powerful Elder Brains, Ulithiards, or Alhoon.

Adherents of Ilsensine

Worshippers of the ancient creator of the Mind Flayers, the adherents are considered a sibling organisation to the ICF. The Adherents take the long view of the subjugation of the 'lesser' species. Their plans span star systems and planes of existence, centuries and millenia.

Specialised Ceremorphs

The Adherents of Ilsensine are responsible for many of the intentionally created ceremorphs, such as Tzakandi and Mozgricken. Others have been co-opted into their designs, weather they ocurred naturally or were developed in independant or allied colonies.

Tzakandi

Shock troops popular among ICF forces, the Ceremorph, Tzakandi arises from ceremorphosis of some lizard folk species. Even neutral illithid groups are known to breed Tzakandi, thinning out the less desireable of their tadpoles while providing them with willing servants.
Tzakandi are brutal, innately cruel, and quiet. They carefully consider situations when outside Illithid direct command, still and silent until they burst into action.

Mozgricken

Scouts and spies of the Adherents, a Ceremorph, Mozgricken was a deep or asteroid gnome prior to ceremorphosis.
Masters of disguise, they are also used as couriers and proxies of Adherent Mind Flayers where suitable.

Brainstealer Dragon

A mix of illithid and dragon, these powerful wyrms occasionally rule over illithid communities that lack an elder brain.

Kezreth

Aliving 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.

Nautiloids

The most common Illithid vessels across the multiverse, the infamous Nautiloid is typically a ceremorph itself (although some colonies construct wooden vessels designed in homage to the gargantuan ceremorphs)
Nautiloids can live for hundreds of years, and there are rumours of ancient paragons among their kind that date back to the Tyrant Era and beyond.
Nautiloid ceremorphosis is a long process, guided by the most accomplished psychometabolic and telepathic mystics among the Illithids.
Some brave pirates and foolhardly adventurers actively hunt older Nautiloids, as they are rumoured to accumulate psionic and magical energies over long life spans, and secrete them into powerful artifacts known as Nucleonic Pearls. References to these pearls is littered throughout multiversal histories, often they are the prizes of deadly conflicts and/or catalysts for massive destruction.

Related Creatures

While the following creatures are offshoots of Mind Flayers, or otherwise genetic relatives, they have not undergone ceremorphosis. For the average spacer, the distinction is irrelevant, as they are just as deadly.

Neothelid

Some academics retain hypothesis that Neothelid are the result of ceremorphosis upon a purple worm, but most scholarly institutions that have undertaken research into illithid tadpoles maintain they are a neotonic offshoot of the Mind Flayers spawn.

Type

Natural