List of legendary creatures (M)
- Maa-alused – Subterranean spirit
- Machlyes – Hermaphroditic humanoid
- Macrocephali – Giant-headed humanoid
- Madam Koi Koi – Female ghost
- Madremonte – Nature guardian
- Maenad
- Maero – Savage, arboreal humanoids
- Magog – Giant protector of London
- Mahaha – Undead humanoids with long, claw-like fingernails
- Maha-pudma – Giant elephant that holds up the world
- Mahuika - Māori fire goddess
- Mairu – Megalith-building giant
- Mājas gari – Benevolent house spirit
- Majitu – in Swahili mythology, shape-shifting spirits that can pass as humans
- Makara – Aquatic beings
- Makura-gaeshi – Pillow-moving spirit
- Mallt-y-Nos – Spirit of the hunt
- Mami Wata – Supernaturally beautiful water spirits
- Mamuna – Demoness or fairy
- Manananggal – Vampires that sever their torsos from their legs to fly around
- Mandi – Humanoid with a forty-year lifespan
- Mandrake – Diminutive humanoid plant
- Manes – Ancestral spirits
- Mannegishi – Little people with six fingers and no noses
- Manticore – Lion-human-scorpion hybrid
- Mapinguari – Giant sloth
- Mara – Female night-demon
- Marabbecca – Malevolent water spirit
- Mare – Malicious entity which causes or appears in bad dreams
- Mareikura – Attendant of Kiho-tumu, the supreme god
- Mares of Diomedes – Man-eating horses
- Marid – Jinn-associated fortune tellers
- Marmennill – Mermen with prophetic abilities
- Maro deivės – Disease spirits
- Marozi – Lion-leopard hybrid
- Maski-mon-gwe-zo-os – Shapeshifting toad spirit
- Matagot – Spirit that takes animal form, usually that of a black cat
- Matsya – First Avatar of Vishnu in the form of a half-fish and half-man
- Mavka – Female forest spirit
- Mayura – Peacock spirit
- Mazzikin – Invisible, malevolent spirit
- Mbói Tu'ĩ – Snake-parrot hybrid
- Mbwiri – Possessing demon
- Medusa – Female human-serpent hybrid with numerous snake heads
- Melek Taus – Divine bird
- Meliae – Ash tree nymph
- Melusine – Female water spirit, with the form of a winged mermaid or serpent
- Menehune – Little people and craftsmen
- Menninkäinen – Little people and nature spirits
- Menreiki – Spiritual creature formed from 66 gigaku masks
- Mephistopheles – Demon or devil
- Merlion – Lion-fish hybrid; the symbol of Singapore
- Mermaid/Merman – Human-fish hybrid
- Merlin – Elderly wizard
- Merrow – Human-fish hybrid
- Metee-kolen-ol – Ice-hearted wizards
- Mimi – Extremely elongated humanoid that has to live in rock crevasses to avoid blowing away
- Minka Bird – Death spirit
- Minokawa – Giant swallow
- Min Min Light – Mysterious light phenomenon
- Minotaur – Human-bull hybrid
- Mintuci – Water spirit
- Mishibizhiw – Feline water spirit
- Misi-ginebig – Serpentine rain spirit
- Misi-kinepikw – Serpentine rain spirit
- Mizuchi – Water dragon
- Mogwai – Vengeful ghost or demon
- Mohan – Nature spirit
- Moirai – Three fates
- Mokèlé-mbèmbé – Water-dwelling creature
- Mokoi – Malevolent spirit that kills sorcerers
- Mokorea – Amphibious humanoid living in the spirit world
- Moñái – Giant snake with antennae
- Mondao – Mermaids/water spirits with long black hair, blood-red eyes, pale skin, and sharp teeth
- Monocerus – One-horned stag-horse-elephant-boar hybrid, sometimes treated as distinct from the unicorn
- Mono Grande – Giant monkey
- Monopod – Dwarf with one giant foot
- Mooinjer veggey – Nature spirit
- Moon rabbit – Legendary animal
- Mora – Disembodied spirit
- Morena – Winter spirit
- Morgens – Water spirits
- Morinji-no-okama – Animated tea kettle
- Mormolykeia – Underworld spirit
- Moroi – Vampiric ghost
- Mo-sin-a – Mountain demon
- Moss people – Little people and tree spirits
- Mothman – Large grey winged humanoid with glowing red eyes
- Mugwump – Fish-like lake monster
- Mujina – Shapeshifting badger spirit
- Muldjewangk – Water monster
- Multo – Spirit of a deceased person seeking justice or with unfinished business
- Mummy – Undead creature who revives
- Muma Pădurii – Forest-dwelling hag
- Mungoon-Gali – Giant goanna
- Muscaliet – Hare-squirrel-boar hybrid that has an intense body heat
- Muse – Spirits that inspire artists
- Mushusshu – Hybrid beast with long neck and eagle talons
- Musimon – Sheep-goat hybrid
- Myling – Ghosts of unbaptized children
- Myrmecoleon – Ant-lion hybrid