| Name | Challenge Rating | Combatants | |
|---|---|---|---|
| Magma Mephit | ½ | 0 | adjudicator |
| Magmin | ½ | 0 | adjudicator |
| Manticore | 0 | 0 | adjudicator |
| Marilith | 16 | 0 | adjudicator |
| Medusa | 6 | 0 | adjudicator |
| Merfolk | ⅛ | 0 | adjudicator |
| Merrow | 2 | 0 | adjudicator |
| Mimic | 2 | 0 | adjudicator |
| Minotaur | 3 | 0 | adjudicator |
| Minotaur Skeleton | 2 | 0 | adjudicator |
| Mummy | 3 | 0 | adjudicator |
| Mummy Lord | 15 | 0 | adjudicator |
| Mummy Lord (in lair) | 16 | 0 | adjudicator |