In the fictional worlds of the Dungeons & Dragons fantasy role-playing game, demodands (gehreleths in 2nd Edition D&D) are a race of fiends native to the Tarterian Depths of Carceri. The gehreleths worship or honor a patron deity called Apomps the Three-sided One, a renegade baernaloth who was exiled to Carceri for the act of creating them. Each of the races has certain peculiarities. The farastu and the kelubar can undergo a lengthy and painful process of self-liquefaction into the secretion they most frequently exude. These pools of tar and slime can be bottled and stored for centuries as a kind of 'instant army'.
The name demodand is derived from deodand, an evil creature in the Dying Earth series by Jack Vance.
The 1st edition Monster Manual II contains the farastu (tarry) demodand, the most common type of demodand, the kelubar (slime) demodand, the bureaucrats of demodand society, and the shator (shaggy) demodand, the disgusting leaders of the demodands.
These creatures appear first in this edition's Monstrous Compendium Outer Planes Appendix as gehreleths, and then in the Planescape Monstrous Compendium Appendix, with the same three kinds described as in first edition.
This edition's Fiend Folio once again describes the farastu, kelubar, and shator demodands. Necromancer Games' The Tome of Horrors also describes the demodands, using their alternative names (tarry, slime, and shaggy).
Demodands feature prominently in the Shackled City Adventure Path, including Dyr’ryd, a massive and deformed shator who founded the Cagewrights. Demodands will also make an appearance with "a different spin" in Paizo Publishing's Pathfinder Chronicles: The Great Beyond book.
Shrieking Terror: Vargouille/hydra crossbreeds created for war and destruction, sometimes used as advance troops by demodands.
Tarterian Creature: Via ancient magical rituals, a creature may gain some of a demodand's power in exchange for surrendering its soul to Carceri upon death. The demodand is destroyed in the process, but gains freedom from the eternal prison plane.
The shator Drigor is trapped within the demiplane of Ravenloft, and the shator Xideous is lurking in the criminally and irreversibly insane ward of the Gatehouse in Sigil, working on a revision to the Book of Keeping. The latter one has a price on his head by the yugoloths. In Gary Gygax's Gord the Rogue series, there is a powerful demodand (presumably a shator), named Utmodach, who works for Nerull. He is the commander of a large group of Demodand warriors.
Wulfgar encounters a farastu in The Halfling's Gem.
The player can visit Carceri (when the city of Curst is shifted into the plane) in the game Planescape: Torment, encountering many hostile farastu. One farastu does communicate with the player, but only to discuss how he wants to eat him...
The shaggy demodand, the slime demodand, and the tarry demodand appeared under the "demodand" heading in the Tome of Horrors (2002) from Necromancer Games.