SRD & OGL creatures — full stat blocks. Each entry links its source.
| Name | Type | Size | CR | Source |
|---|---|---|---|---|
| Marilith | Fiend | large | 16 | Black Flag SRD |
| Marsh Dire | Undead | Medium | 8 | Tome of Beasts 2 |
| Mask Wight | Undead | Medium | 13 | Tome of Beasts 2023 |
| Mask Wight | Undead | Medium | 13 | Tome of Beasts |
| Massive Malleable | Aberration | Gargantuan | 16 | Tome of Beasts 2 |
| Master Alchemist | Humanoid | medium | 7 | Black Flag SRD |
| Master Assassin | Humanoid | Medium | 17 | Level Up Advanced 5e Monstrous Menagerie |
| Master Thief | Humanoid | Medium | 17 | Level Up Advanced 5e Monstrous Menagerie |
| Matriarch Serpentine Lamia | Monstrosity | Large | 5 | Creature Codex |
| Mavka | Undead | Medium | 12 | Tome of Beasts 2023 |
| Mavka | Undead | Medium | 12 | Tome of Beasts |
| Mead Archon | Celestial | Medium | 4 | Tome of Beasts 2 |
| Mechanist | Humanoid | medium | 2 | Black Flag SRD |
| Mechuiti | Fiend | Gargantuan | 27 | Tome of Beasts 2023 |
| Medusa | Monstrosity | medium | 6 | Black Flag SRD |
| Medusa | Monstrosity | Medium | 7 | Level Up Advanced 5e Monstrous Menagerie |
| Medusa | Monstrosity | Medium | 6 | 5e Core Rules |
| Medusa Queen | Monstrosity | Medium | 11 | Level Up Advanced 5e Monstrous Menagerie |
| Megapede | Monstrosity | Large | 3 | Creature Codex |
| Merclops | Giant | Huge | 7 | Level Up Advanced 5e Monstrous Menagerie |
| Merfolk | Humanoid | medium | 1/8 | Black Flag SRD |
| Merfolk | Humanoid | Medium | 1/8 | 5e Core Rules |
| Merfolk | Humanoid | Medium | 1/8 | Level Up Advanced 5e Monstrous Menagerie |
| Merfolk Knight | Humanoid | Medium | 3 | Level Up Advanced 5e Monstrous Menagerie |
| Merrow | Monstrosity | Large | 2 | 5e Core Rules |
| Merrow | Monstrosity | Large | 2 | Level Up Advanced 5e Monstrous Menagerie |
| Merrow | Monstrosity | large | 2 | Black Flag SRD |
| Merrow Mage | Monstrosity | Large | 4 | Level Up Advanced 5e Monstrous Menagerie |
| Mi-Go | Plant | Medium | 5 | Tome of Beasts |
| Mi-Go | Plant | Medium | 5 | Tome of Beasts 2023 |
| Midnight Sun | Aberration | Large | 7 | Tome of Beasts 3 |
| Millitaur | Monstrosity | Large | 3 | Tome of Beasts |
| Millitaur | Monstrosity | Large | 3 | Tome of Beasts 2023 |
| Mimic | Monstrosity | Medium | 2 | 5e Core Rules |
| Mimic | Monstrosity | medium | 2 | Black Flag SRD |
| Mimic | Monstrosity | Medium | 2 | Level Up Advanced 5e Monstrous Menagerie |
| Mindrot Thrall | Plant | Medium | 3 | Tome of Beasts 2023 |
| Mindrot Thrall | Plant | Medium | 3 | Tome of Beasts |
| Mindshard | Aberration | Small | 4 | Tome of Beasts 3 |
| Beast |
| Medium |
| 1/8 |
| 5e Core Rules |
| Beast |
| Medium |
| 1/8 |
| Level Up Advanced 5e Monstrous Menagerie |
| Beast |
| medium |
| 1/8 |
| Black Flag SRD |
| Beast |
| Huge |
| 3 |
| Tome of Beasts |
| Beast |
| Huge |
| 3 |
| Tome of Beasts 2023 |
| Beast |
| Tiny |
| 0 |
| Tome of Beasts 3 |
| Beast |
| Medium |
| 1/2 |
| Tome of Beasts 3 |
| Beast |
| Medium |
| 2 |
| Tome of Beasts 3 |
| Beast |
| Gargantuan |
| 7 |
| Tome of Beasts 2 |