In many campaign settings for the Dungeons & Dragons role-playing game, Maanzecorian is the illithid deity of knowledge and philosophy.^[1] His symbol is a silver crown set with a red gem.

Maanzecorian was killed by Tenebrous while the latter was trying to return to his former existence as the Demon Prince Orcus.^[2]

Maanzecorian first appeared in second edition AD&D in Monster Mythology (1992).^[1] His death was reported in the Planescape adventure Dead Gods (1997), and depicted on page 37, with its aftereffects depicted on page 18.^[2]

Maanzecorian appeared as a 10-foot-tall (3.0 m) illithid with purple and green skin and yellowed tusks on either side of his tentacles. A silver crown always levitated above his head. The gem set in his crown acts as a gem of brightness, though this light creates no negative effects for illithids.

Maanzecorian was always deferential to Ilsensine, although he did keep some secrets from the more powerful deity.

The philosopher-god sometimes dispatched avatars to meditate or share knowledge with his small priesthood or, on particularly propitious occasions, to help negotiate with other races.

Two of Maanzecorian's servants were illithids called Hananolith and Dleniacorus. Both of them died shortly after their master.

Maanzecorian's realm of Rictus was located on the plane of Gehenna. He has a vast library of arcane works in his palace. His palace is sumptuously furnished with jet, jade, ivory, marble, and skins of many different creatures.

A portal from Rictus led to Chariamur, an old open-pit mine located between the realms of Ilsensine and Gzemnid in the Outlands, where servants of Maanzecorian would come to spy on Ilsensine. The Rotting Oracle was a former temple to Juiblex built in the bottom of the mine; two pillars in the half-sunken building formed the portal.

Maanzecorian believes that illithids are the natural masters of all the multiverse, and that other races are only fit to be food or slaves. However, unlike his master Ilsensine, Maanzecorian believes that there are some things that illithids may profitably learn from other races before devouring them, and that the pleasure of eating is even greater after lingering to anticipate it.

Maanzecorian's small priesthood concerned itself with the pursuit of knowledge, exploration of new territory, and the exploiting of knowledge they had gained. They would negotiate with other races, but only from a position of strength.

A sealed, ruined temple on the distant world of Penumbra contains Maanzecorian's last, faded avatar. If this avatar is destroyed, the last vestige of Maanzecorian's power will have vanished from the multiverse.^[3]: 22

Maanzecorian was already a deity long ago, when the great illithid empire dominated multiple worlds and planes. At least one temple was erected to him on distant Penumbra, the illithid capital; this temple was abandoned after the ancestors of the githyanki overthrew the empire.

Tenebrous (the undead spirit of he who once was Orcus) sought out many gods of knowledge in an attempt to find a deity who knew the location of his lost Wand. One of the first of his victims was Maanzecorian; Tenebrous used the Last Word, a powerful magical effect, to strike the god dead. Tenebrous then stood over the corpse of the deity, absorbing the eons of collected secrets the dead deity released. Unfortunately, none of the secrets were the location of Orcus's wand, forcing Tenebrous to continue his quest elsewhere.

• Grubb, Jeff, David Noonan, and Bruce Cordell. Manual of the Planes. Renton, WA: Wizards of the Coast, 2001. Page 111.
• McComb, Colin. On Hallowed Ground. Lake Geneva, WI: TSR, 1996.