In the Dungeons & Dragons fantasy role-playing game, an obyrith is a member of an ancient race of demons that predate the tanar'ri. All obyriths have monstrous forms which can drive mad anyone who dares look at them.
The concept of the obyrith type of demon was introduced in the third edition in the Fiendish Codex I: Hordes of the Abyss (2006). This book introduced the ekolid and the sibriex, as well as the demon lord Dagon. The laghathti was introduced on the Wizards of the Coast website in 2006. Dagon, Prince of the Darkened Depths, was detailed in Dragon #349 (November 2006), which introduced the uzollru. The draudnu appeared in Monster Manual V (2007), the Golothoma in Elder Evils and the verakia appeared in Dragon #357 (July 2007).
Heavily reworked obyriths make an appearance in the 4th edition of Dungeons & Dragons. In the Demonomicon supplement, the obyriths are described as entities of unfathomable evil from another universe. After consuming or destroying everything in their universe, the remaining obyriths fashioned all of their hatred and hunger into a single, horrific shard of pure evil, which they used to pierce the veil between universes. The shard was found (in the default D&D universe) by Tharizdun, who was instantly corrupted by its evil and used it to create the Abyss. The twelve surviving Obyriths fled their dying reality and entered the new plane, where they dueled several primordials- the beings who would eventually become the likes of Baphomet, Demogorgon, Orcus, and Yeenoghu- for control. The Abyss warped both the obyriths and the primordials into demon lords. In the new edition, only the Queen of Chaos, Pazuzu, Obox-ob and Dagon are explicitly confirmed as being obyriths; it is left to the DM to decide which of the other demon lords are obyriths.
Types of Obyriths
- Draudnu: Has three, long, spindly legs that support and attach to its body at the top. Swollen sacs of fluid bulge from its barrel-shaped body, which terminates beneath with a single red eye, around which extend three hooked appendages. These ruthless killers seek to rid the Abyss of non-obyriths, corrupting the minds and destroying the bodies of creatures they encounter.
- Ekolid: Resembling the union of an ant, a scorpion and a spider, these vermin-like obyriths live in swarms, except on Zionyn (663rd layer of the Abyss), where they build huge, resinous cities in honor of their master and patron, the demon lord Obox-ob.
- Golothoma: Mouthless, cyclopean and serpentine, these obyriths live by consuming creatures caught in their supernatural shadow. They are also capable of reaching between dimensions and attacking far away foes with its spider-like claws that circle its single eye.
- Laghathti: Laghathti resemble oily black octopuses. They lurk near the surface of the River Styx, where they steal memories from their victims.
- Sibriex: Sybriexes resemble enormous deformed faces floating in the air, linked to the ground by metal chains. Sybriexes enjoy modeling flesh, and are rumored to have a role in the shaping of the forms of the tanar'ri.
- Uzollru: Uzollru resemble massive aquatic centipedes, with fins rather than legs, and a head sporting a single red eye ringed by feeding tentacles. They primarily serve the demon prince Dagon in his realm of Shadowsea.
- Verakia: Verakia are huge, dragon-like obyriths who live in Demogorgon's realm. They are mindless beasts, and anyone who sees a Verakia becomes a mindless killer.
Several notable demon lords are obyriths.
- Dagon: Prince of the Darkened Depths.
- Obox-ob: Prince of Vermin.
- Pale Night: Mother of Demons.
- Pazuzu: Prince of the Lower Aerial Kingdoms. His form does not drive anyone mad: instead, he inspires worshipful obedience from all flying creatures of evil alignment.
- Queen of Chaos: Led the side of Chaos in the battle against the Wind Dukes of Aaqa in the Age Before Ages.
- Sertrous, Prince of Heretics
- Asima, the Unanticipated
- Bechard, Lord of Tempests, the Rotting Husk
- Kizarvidexus 
- The Malgoth
- Jacobs, James, Erik Mona, and Ed Stark. Fiendish Codex I: Hordes of the Abyss (Wizards of the Coast, 2006)
- Fiendish Codex I: The Lost Annals
- Jacobs, James. "The Demonimicon of Iggwilv: Dagon." Dragon #349 (Paizo Publishing, 2006)
- Mearls, Mike, Brian R. James, and Steve Townshend. Demonomicon. (Wizards of the Coast, 2010)
- Dragon #357, page 69
- Elder Evils, page 112
- Dungeon #148, "Wells of Darkness", page 66
- Fiendish Codex I p 125
- Dragon #349 "Demonomicon of Iggwilv", page 31
- Dragon #333 "Demonomicon of Iggwilv", page 39.
- Dragon #345, "Demonomicon of Iggwilv", page 31.
- Dragon #349 "Demonomicon of Iggwilv", page 31.