- Metaion, the Timelord
- Metal Armored Bug
- Metal Dragon
- Metal Guardian
- Metalmorph
- Metalzoa
- Metamorphosis
- Meteor Dragon
- Meteor of Destruction
- Meteorain
- Michizure
- Mid Shield Gardna
- Mimesis
- Mind Control
- Mine Golem
- Mine Mole
- Minefield Eruption
- Mini-Guts
- Mira the Star-Bearer
- Miracle
- Miracle Fusion
- Miracle Kids
- Miracle's Wake
- Mirage Dragon