| Ancient copper dragon | 21 | Dragon | Gargantuan | 21 | 350 | fly | chaotic good | Legendary | Monster Manual (SRD) | 27 | 12 | 25 | 20 | 17 | 19 |
| Ancient bronze dragon | 22 | Dragon | Gargantuan | 22 | 444 | fly, swim | lawful good | Legendary | Monster Manual (SRD) | 29 | 10 | 27 | 18 | 17 | 21 |
| Ancient brass dragon | 20 | Dragon | Gargantuan | 20 | 297 | fly | chaotic good | Legendary | Monster Manual (SRD) | 27 | 10 | 25 | 16 | 15 | 19 |
| Ancient blue dragon | 23 | Dragon | Gargantuan | 22 | 481 | fly | lawful evil | Legendary | Monster Manual (SRD) | 29 | 10 | 27 | 18 | 17 | 21 |
| Ancient black dragon | 21 | Dragon | Gargantuan | 22 | 367 | fly, swim | chaotic evil | Legendary | Monster Manual (SRD) | 27 | 14 | 25 | 16 | 15 | 19 |
| Amnizu | 18 | Fiend (devil) | Medium | 21 | 202 | fly | lawful evil | | Mordenkainen's Tome of Foes | | | | | | |
| Ambush drake | 0.5 | Dragon | Medium | 13 | 22 | | unaligned | | Adventures (Tyranny of Dragons) | | | | | | |
| Allosaurus | 2 | Beast | Large | 13 | 51 | | unaligned | | Monster Manual (SRD) | 19 | 13 | 17 | 2 | 12 | 5 |
| Allip | 5 | Undead | Medium | 13 | 40 | fly | neutral evil | | Mordenkainen's Tome of Foes | | | | | | |
| Alkilith | 11 | Fiend (demon) | Medium | 17 | 157 | | chaotic evil | | Mordenkainen's Tome of Foes | | | | | | |
| Alhoon | 10 | Undead | Medium | 15 | 120 | | any evil alignment | | Volo's Guide to Monsters | | | | | | |
| Aldani | | Monstrosity | Medium | 0 | 0 | swim | lawful neutral | | Adventures (Tomb of Annihilation) | | | | | | |
| Albino dwarf warrior | 0.25 | Humanoid (dwarf) | Medium | 13 | 30 | | any alignment | | Adventures (Tomb of Annihilation) | | | | | | |
| Air elemental myrmidon | 7 | Elemental | Medium | 18 | 117 | fly | neutral | | Mordenkainen's Tome of Foes | | | | | | |
| Air elemental | 5 | Elemental | Large | 15 | 90 | fly | neutral | | Monster Manual (SRD) | 14 | 20 | 14 | 6 | 10 | 6 |
| Adult white dragon | 13 | Dragon | Huge | 18 | 200 | fly, swim | chaotic evil | Legendary | Monster Manual (SRD) | 22 | 10 | 22 | 8 | 12 | 12 |
| Adult silver dragon | 16 | Dragon | Huge | 19 | 243 | fly | lawful good | Legendary | Monster Manual (SRD) | 27 | 10 | 25 | 16 | 13 | 21 |
| Adult red dragon | 17 | Dragon | Huge | 19 | 256 | fly | chaotic evil | Legendary | Monster Manual (SRD) | 27 | 10 | 25 | 16 | 13 | 21 |
| Adult oblex | 5 | Ooze | Medium | 14 | 75 | | lawful evil | | Mordenkainen's Tome of Foes | | | | | | |
| Adult kruthik | 2 | Monstrosity | Medium | 18 | 39 | | unaligned | | Mordenkainen's Tome of Foes | | | | | | |
| Adult green dragon | 15 | Dragon | Huge | 19 | 207 | fly, swim | lawful evil | Legendary | Monster Manual (SRD) | 23 | 12 | 21 | 18 | 15 | 17 |
| Adult gold dragon | 17 | Dragon | Huge | 19 | 256 | fly, swim | lawful good | Legendary | Monster Manual (SRD) | 27 | 14 | 25 | 16 | 15 | 24 |
| Adult copper dragon | 14 | Dragon | Huge | 18 | 184 | fly | chaotic good | Legendary | Monster Manual (SRD) | 23 | 12 | 21 | 18 | 15 | 17 |
| Adult bronze dragon | 15 | Dragon | Huge | 19 | 212 | fly, swim | lawful good | Legendary | Monster Manual (SRD) | 25 | 10 | 23 | 16 | 15 | 19 |
| Adult brass dragon | 13 | Dragon | Huge | 18 | 172 | fly | chaotic good | Legendary | Monster Manual (SRD) | 23 | 10 | 21 | 14 | 13 | 17 |