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- Madame Web
- Mad Titan
- Magda
- Magician (Boggs, Elliot)
- Magneto (Lensherr, Erik)- dead
- Marvel Girl (Grey, Jean)
- Man-Ape (M'baku)
- Mandarin
- Man-Thing (Sallis, Ted)
- Mark Raxton
- Mary Parker
- Mary Jane Watson
- Master Menace (Emil Burbank) (Squadron Supreme)
- Mastermind (unknown)
- Maximus
- May Parker
- Melissa Beckerman
- Mephisto
- Miles Warren
- Miles Bullock "Captain Winter"
- Miles Morales
- Mister Fantastic (Richards, Reed)
- Mister Fantastic (Richards, Reed) (Marvel zombies)
- Mister Golog
- Mister Nix
- Mr. Rose
- Ms. Marvel
- MODOK (Tarleton, George)
- Mojo Adams
- Mole Man (Molekevic, Arthur)
- Morbius (unknown, but implied to be the son of Vlad Tepes Dracula)
- Moira MacTaggert
- Magnificent Brute
- Morlocks
- Montana (Bale, Montana)
- Moondragon (Douglas, Heather)
- Medusa
- Moon Knight (Spector, Marc)
- Multiple Man (Madrox, James) - dead
- Mysterio
- Mystique (unknown)
Read more about this topic: List Of Ultimate Marvel Characters