This list includes 26 Mythical creatures that start with O, from “Oannes” to “Ox‑Head”. The entries span global traditions and suit research, worldbuilding, classroom use, and gaming.
Mythical creatures that start with O are legendary beings from folklore and myth, often linked to culture-specific themes. For example, Oannes appears in Mesopotamian lore as a wise, half-fish teacher.
Below you’ll find the table with Name, Origin, Description, Famous stories, and Alternate names.
Name: The creature’s common English name; you can use it for searching, citations, or naming characters and monsters.
Origin: A short cultural or geographic label showing myth origin; you use it to compare traditions and historical context.
Description: A concise two-sentence summary of appearance, powers, or role that helps you quickly assess relevance.
Famous stories: Key myths, epics, or texts where the creature appears, so you can follow original accounts or further reading.
Alternate names: Other names, spellings, or titles used across cultures, useful for cross-referencing and deeper searches.
Mythical creatures that start with O
| Name | Alternate names | Origin culture | Notable sources |
|---|---|---|---|
| Oni | demon, ogre | Japanese folklore | Kojiki; Nihon Shoki; folktales |
| Ogre | ogre | European folklore | Charles Perrault; Grimm tales; folktales |
| Orthrus | Orthus, Orthros | Greek myth | Hesiod; Apollodorus; Heracles cycles |
| Ouroboros | uroboros | Ancient Egyptian / Greek alchemy | Egyptian iconography; Chrysopoeia of Cleopatra; Gnostic texts |
| Oread | oreads, mountain nymphs | Greek | Hesiod; Ovid; Greek poetry |
| Oannes | Oan, Uanna | Mesopotamian / Babylonian | Berossus; Diodorus Siculus; Babylonian tradition |
| Ophion | Ophion | Greek (Orphic) | Orphic fragments; Diodorus Siculus; Orphic cosmogony |
| Ophiotaurus | ophiotauros, bull‑serpent | Greek myth | Orphic fragments; classical scholia; myth compendia |
| Oneiroi | Oneiros, dream‑spirits | Greek | Homer’s Odyssey; Hesiod; Greek poetry |
| Orobas | Orobas | Medieval grimoires / demonology | Ars Goetia (Lesser Key of Solomon); Pseudomonarchia Daemonum |
| Oberon | king of the fairies | Medieval European | Huon of Bordeaux; Shakespeare’s A Midsummer Night’s Dream; The Faerie Queene |
| Otso | Otso (Great Bear) | Finnish | Kalevala; Finnish folk tradition |
| Onocentaur | onocentaur, ass‑centaur | Medieval bestiary | Physiologus; Isidore of Seville; medieval bestiaries |
| Orc | orc, ork | Old English / Medieval European | Beowulf; Old English literature; medieval glosses |
| Ogopogo | Ogopogo | Indigenous Okanagan / Canadian folklore | Secwepemc / Okanagan legends; local oral tradition |
| Ox‑Head | Niu‑tou (Ox‑Head) | Chinese | Journey to the West; Chinese folk religion |
| Onibaba | onibaba, demon hag | Japanese folklore | Heike Monogatari; regional folktales |
| Obake | bakemono, obake | Japanese folklore | Kojiki; folktales; yōkai collections |
| Ongon | ongon (spirit‑idol) | Mongolian / Tuvan shamanism | Mongolian folklore; ethnographic accounts |
| Ojáncanu | ojáncanu | Cantabrian (northern Spain) | Cantabrian folktales; regional legends |
| Oilliphéist | oilliphéist | Irish | Irish folklore; county legends |
| Old Hag | Old Hag (night hag) | English / North American folklore | Newfoundland tales; sleep‑paralysis folklore; Appalachian stories |
| Ose | Ose, Oze | Goetic demonology | Ars Goetia; Pseudomonarchia Daemonum |
| Orias | Orias, Oriax | Goetic demonology | Ars Goetia; Pseudomonarchia Daemonum |
| Orochi | Yamata‑no‑Orochi | Japanese | Kojiki; Nihon Shoki; folk legends |
| Ondine | undine, ondina | European (Renaissance / folklore) | Paracelsus; Renaissance elemental lore; Romantic tales |
Descriptions
Oni
Horned, club‑wielding ogres or demons in Japanese folklore who punish wrongdoers and appear in myths, festivals, and countless regional tales.
Ogre
Large, man‑eating humanoid from European fairy tales and oral tradition; brutish antagonist often used to frighten or moralize in folk stories.
Orthrus
Two‑headed dog, brother of Cerberus, who guarded Geryon’s cattle and was slain by Heracles during his tenth labor.
Ouroboros
Serpent or dragon that bites its own tail, symbolizing cyclicality, eternity, and self‑renewal across Egyptian, Greek alchemical, and Gnostic traditions.
Oread
Mountain nymphs—nature spirits of high places associated with Artemis—appearing across Greek poetry and myth as graceful, wild companions.
Oannes
A fish‑headed culture‑bringer who emerged from the sea to teach humans writing and law in Babylonian accounts recorded by Berossus.
Ophion
Primordial serpent or Titan who briefly ruled the cosmos with Eurynome before being overthrown by the Olympian gods in Orphic myth.
Ophiotaurus
Hybrid creature part bull, part serpent; legend held that burning its entrails could grant victory to the sacrificer—an obscure but striking Greek motif.
Oneiroi
Personified spirits of dreams that deliver messages, omens or prophetic visions to mortals during sleep in Homeric and Hesiodic tradition.
Orobas
Goetic spirit from Renaissance grimoires, said to answer questions truthfully and grant protection—part of European occult folklore.
Oberon
Fairy king in medieval romance and later literature; ruler of the fairy court with variable roles in folklore and drama.
Otso
Sacred bear spirit central to Finnish folklore, revered as ancestor and powerful forest being with ritual observances recorded in Kalevala.
Onocentaur
Half‑man, half‑donkey monstrous humanoid in medieval bestiaries, moralized as a symbol of base instincts and vice.
Orc
Originally a monstrous demon or death‑spawn in Old English poetry (e.g., “orcneas” in Beowulf), later evolving into modern fantasy orcs.
Ogopogo
Lake monster of Okanagan Lake, rooted in Indigenous legend and later cryptid sightings, typically described as a serpentine or eel‑like creature.
Ox‑Head
One of the underworld guardians—paired with Horse‑Face—who seizes and escorts souls to the afterlife in Chinese popular belief.
Onibaba
A fearsome “demon hag” in Japanese legend who preys on travelers; blends oni features with ghostly, cannibalistic motifs in medieval tales.
Obake
Generic term for shape‑shifting “changed things” in Japanese folklore: ghosts, monsters, and tricksters that transform or haunt humans.
Ongon
Ancestral or local spirit housed in ritual objects; invoked by shamans as a protector, guide, or source of power in steppe religions.
Ojáncanu
Gigantic, hairy, club‑wielding giants from Cantabrian folklore who menace humans and are defeated by local heroes in mountain tales.
Oilliphéist
Water‑serpent or lake monster of Irish tradition, often associated with tales of monstrous aquatic beasts slain by heroes in local lore.
Old Hag
Witch‑like nocturnal creature blamed for sleep paralysis and night terrors; sits on victims’ chests in a widespread folkloric motif.
Ose
Spirit listed in medieval and Renaissance grimoires, associated with transformations and inducing foolishness in European demonology.
Orias
Marquis of Hell in Renaissance grimoires, depicted as a mounted warrior; part of occult folklore and ceremonial magic lists.
Orochi
Eight‑headed and eight‑tailed serpent slain by the storm god Susanoo in Japanese myth; a prime example of monstrous serpentine foes.
Ondine
Water nymph or elemental spirit tied to lakes and streams, popularized by Paracelsian elemental theory and Romantic literature.