| Iron golem | 16 | Construct | Large | 20 | 210 | | unaligned | | Monster Manual (SRD) | 24 | 9 | 20 | 3 | 11 | 1 |
| Iron consul | 2 | Humanoid (human) | Medium | 16 | 45 | | lawful evil | | Adventures (Descent into Avernus) | | | | | | |
| Iron cobra | 4 | Construct | Medium | 13 | 45 | | unaligned | | Mordenkainen's Tome of Foes | | | | | | |
| Invisible stalker | 6 | Elemental | Medium | 14 | 104 | fly | neutral | | Monster Manual (SRD) | 16 | 19 | 14 | 10 | 15 | 11 |
| Intellect devourer | 2 | Aberration | Tiny | 12 | 21 | | lawful evil | | Monster Manual | | | | | | |
| Imp | 1 | Fiend (devil, shapechanger) | Tiny | 13 | 10 | fly | lawful evil | | Monster Manual (SRD) | 6 | 17 | 13 | 11 | 12 | 14 |
| Imix | 19 | Elemental | Huge | 17 | 325 | fly | neutral evil | | Adventures (Princes of the Apocalypse) | | | | | | |
| Illusionist | 3 | Humanoid (any race) | Medium | 12 | 38 | | any alignment | | Volo's Guide to Monsters | | | | | | |
| Ice toad | 1 | Monstrosity | Medium | 12 | 32 | swim | neutral | | Adventures (Tyranny of Dragons) | | | | | | |
| Ice mephit | 0.5 | Elemental | Small | 11 | 21 | fly | neutral evil | | Monster Manual (SRD) | 7 | 13 | 10 | 9 | 11 | 12 |
| Ice devil | 14 | Fiend (devil) | Large | 18 | 180 | | lawful evil | | Monster Manual (SRD) | 21 | 14 | 18 | 18 | 15 | 18 |
| Hyena | 0 | Beast | Medium | 11 | 5 | | unaligned | | Monster Manual (SRD) | 11 | 13 | 12 | 2 | 12 | 5 |
| Hydroloth | 9 | Fiend (yugoloth) | Medium | 15 | 135 | swim | neutral evil | | Mordenkainen's Tome of Foes | | | | | | |
| Hydra | 8 | Monstrosity | Huge | 15 | 172 | swim | unaligned | | Monster Manual (SRD) | 20 | 12 | 20 | 2 | 10 | 7 |
| Hutijin | 21 | Fiend (devil) | Large | 19 | 200 | fly | lawful evil | | Mordenkainen's Tome of Foes | | | | | | |
| Hunter shark | 2 | Beast | Large | 12 | 45 | swim | unaligned | | Monster Manual (SRD) | 18 | 13 | 15 | 1 | 10 | 4 |
| Hulking crab | 5 | Beast | Huge | 17 | 76 | swim | unaligned | | Adventures (Storm King's Thunder) | | | | | | |
| Howler | 8 | Fiend | Large | 16 | 90 | | chaotic evil | | Mordenkainen's Tome of Foes | | | | | | |
| Horned devil | 11 | Fiend (devil) | Large | 18 | 178 | fly | lawful evil | | Monster Manual (SRD) | 22 | 17 | 21 | 12 | 16 | 17 |
| Hook horror | 3 | Monstrosity | Large | 15 | 75 | | neutral | | Monster Manual (BR) | 18 | 10 | 15 | 6 | 12 | 7 |
| Homunculus | 0 | Construct | Tiny | 13 | 5 | fly | neutral | | Monster Manual (SRD) | 4 | 15 | 11 | 10 | 10 | 7 |
| Hobgoblin warlord | 6 | Humanoid (goblinoid) | Medium | 20 | 97 | | lawful evil | | Monster Manual | | | | | | |
| Hobgoblin iron shadow | 2 | Humanoid (goblinoid) | Medium | 15 | 32 | | lawful evil | | Volo's Guide to Monsters | 14 | 16 | 15 | 14 | 15 | 11 |
| Hobgoblin devastator | 4 | Humanoid (goblinoid) | Medium | 13 | 45 | | lawful evil | | Volo's Guide to Monsters | | | | | | |
| Hobgoblin captain | 3 | Humanoid (goblinoid) | Medium | 17 | 39 | | lawful evil | | Monster Manual (BR) | 15 | 14 | 14 | 12 | 10 | 13 |