| Assassin | 8 | Humanoid (any race) | Medium | 15 | 78 | | any non-good alignment | | Monster Manual (SRD) | 11 | 16 | 14 | 13 | 11 | 10 |
| Assassin vine | 3 | Plant | Large | 13 | 85 | | unaligned | | Adventures (Tomb of Annihilation) | | | | | | |
| Astral dreadnought | 21 | Monstrosity (titan) | Gargantuan | 20 | 297 | fly | unaligned | Legendary | Mordenkainen's Tome of Foes | 28 | 7 | 25 | 5 | 14 | 18 |
| Atropal | 13 | Undead (titan) | Huge | 7 | 225 | fly | neutral evil | | Adventures (Tomb of Annihilation) | | | | | | |
| Aurochs | 2 | Beast | Large | 11 | 38 | | unaligned | | Volo's Guide to Monsters | 20 | 10 | 19 | 2 | 12 | 5 |
| Autumn eladrin | 10 | Fey (elf) | Medium | 19 | 127 | | chaotic neutral | | Mordenkainen's Tome of Foes | | | | | | |
| Awakened shrub | 0 | Plant | Small | 9 | 10 | | unaligned | | Monster Manual (SRD) | 3 | 8 | 11 | 10 | 10 | 6 |
| Awakened tree | 2 | Plant | Huge | 13 | 59 | | unaligned | | Monster Manual (SRD) | 19 | 6 | 15 | 10 | 10 | 7 |
| Axe beak | 0.25 | Beast | Large | 11 | 19 | | unaligned | | Monster Manual (SRD) | 14 | 12 | 12 | 2 | 10 | 5 |
| Azer | 2 | Elemental | Medium | 17 | 39 | | lawful neutral | | Monster Manual (SRD) | 17 | 12 | 15 | 12 | 13 | 10 |
| Babau | 4 | Fiend (demon) | Medium | 16 | 82 | | chaotic evil | | Volo's Guide to Monsters | | | | | | |
| Baboon | 0 | Beast | Small | 12 | 3 | | unaligned | | Monster Manual (SRD) | 8 | 14 | 11 | 4 | 12 | 6 |
| Bael | 19 | Fiend (devil) | Large | 18 | 189 | | lawful evil | | Mordenkainen's Tome of Foes | | | | | | |
| Balhannoth | 11 | Aberration | Large | 17 | 114 | | chaotic evil | | Mordenkainen's Tome of Foes | | | | | | |
| Balor | 19 | Fiend (demon) | Huge | 19 | 262 | fly | chaotic evil | | Monster Manual (SRD) | 26 | 15 | 22 | 20 | 16 | 22 |
| Banderhobb | 5 | Monstrosity | Large | 15 | 84 | | neutral evil | | Volo's Guide to Monsters | | | | | | |
| Bandit | 0.12 | Humanoid (any race) | Medium | 12 | 11 | | any non-lawful alignment | | Monster Manual (SRD) | 11 | 12 | 12 | 10 | 10 | 10 |
| Bandit captain | 2 | Humanoid (any race) | Medium | 15 | 65 | | any non-lawful alignment | | Monster Manual (SRD) | 15 | 16 | 14 | 14 | 11 | 14 |
| Banshee | 4 | Undead | Medium | 12 | 58 | fly | chaotic evil | | Monster Manual (SRD) | 1 | 14 | 10 | 12 | 11 | 17 |
| Baphomet | 23 | Fiend (demon) | Huge | 22 | 275 | | chaotic evil | | Mordenkainen's Tome of Foes | | | | | | |
| Barbed devil | 5 | Fiend (devil) | Medium | 15 | 110 | | lawful evil | | Monster Manual (SRD) | 16 | 17 | 18 | 12 | 14 | 14 |
| Bard | 2 | Humanoid (any race) | Medium | 15 | 44 | | any alignment | | Volo's Guide to Monsters | | | | | | |
| Barghest | 4 | Fiend (shapechanger) | Large | 17 | 90 | | neutral evil | | Volo's Guide to Monsters | 19 | 15 | 14 | 13 | 12 | 14 |
| Barlgura | 5 | Fiend (demon) | Large | 15 | 68 | | chaotic evil | | Monster Manual (BR) | 18 | 15 | 16 | 7 | 14 | 9 |
| Basilisk | 3 | Monstrosity | Medium | 15 | 52 | | unaligned | | Monster Manual (SRD) | 16 | 8 | 15 | 2 | 8 | 7 |