legendary beings list : O

• Obake (Japanese) - Shapeshifting spirits
• Obambo (Central African) - Homeless ghost
• Obariyon (Japanese) - Spook which rides piggyback on a human victim and becomes unbearably heavy
• Obayifo (Ashanti) - Vampiric possession spirit
• Obia (West Africa) - Gigantic animal that serves witches
• Oceanid (Greek) - Nymph daughters of Oceanus
• Odei (Basque) - Storm spirit
• Odmience (Slavic) - Changeling
• Og (Jewish) - Giant king of the Amorites
• Ogre (Medieval folklore) - Large, grotesque humanoid
• Oiwa (Japanese) - Ghost of a woman with a distorted face who was murdered by her husband
• Ojáncanu (Cantabrian) - Giant cyclop who embodies the evil.
• Okiku (Japanese) - Plate-counting ghost of a servant girl
• Okuri-inu (Japanese) - Dog or wolf that follows travelers at night. Similar to the Black dog of English folklore
• Ole-Higue (Guyanese) - Vampiric hag who takes the form of a fireball at night
• Ōmukade (Japanese) - Giant, human-eating centipede that lives in the mountains
• Oni (Japanese) - Large, grotesque humanoid
• Onibi (Japanese) - Spectral fire
• Onmoraki (Japanese) - Bird-demon created from the spirits of freshly-dead corpses
• Onocentaur (Medieval Bestiaries) - Human-donkey hybrid
• Onoskelis (Greek) - Shapeshifting demon
• Onryō (Japanese) - Vengeful ghost that manifests in physical (rather than spectral) form
• Onza (Aztec and Latin American folklore) - Wild cat, possibly a subspecies of cougar
• Oozlum bird (Unknown origin) - Bird that flies backwards
• Ophiotaurus (Greek) - Bull-serpent hybrid
• Opinicus (Heraldic) - Lion-eagle hybrid, similar to a griffin, but with leonine forelimbs
• Orang Bunian (Malay) - Forest spirit
• Orang Minyak (Malay) - Spectral rapist
• Ördög (Hungarian) - Shapeshifting demon
• Oread (Greek) - Mountain nymph
• Ork ( Tyrolean) - Little people and house spirits
• Orobas (European) - Horse-headed, honest oracle classed as a demon
• Orphan Bird (Medieval Bestiaries) - Peacock-eagle-swan-crane hybrid
• Orthrus (Greek) - Two-headed dog
• Otso (Finnish) - Bear spirit
• Ouroboros (Worldwide) - Mystic serpent/dragon that eats its own tail
• Ovinnik (Slavic) - Malevolent threshing house spirit