| Name | CR | Type | Environment |
| Ihonva | 4 | monstrous humanoid | warm desert (Verces) |
| Ijtikri | 1/2 | aberration | any (Vesk-2) |
| Ijtikri, Ijtikri Commando | 4 | aberration | any (Vesk-2) |
| Ikeshti, Ikeshti Brood-Minder | 2 | humanoid (ikeshti) | any deserts, hills, or mountains (Akiton) |
| Ikeshti, Ikeshti Rivener | 5 | humanoid (ikeshti) | any deserts, hills, or mountains (Akiton) |
| Ilthisarian | 4 | monstrous humanoid (ilthisarian) | any swamp (Arshalin) |
| Impostor | 8 | outsider (extraplanar) | any (Astral Plane) |
| Inevitable, Anhamut | 10 | outsider (inevitable, lawful) | any |
| Irokiroi | 5 | animal | any sky (Osoro) |
| Irokiroi, Oshirokiroi | 12 | animal | any sky (Osoro) |
| Izalguun, Izalguun Healer | 8 | monstrous humanoid | any (Izalraan) |
| Izalguun, Izalguun Hunter | 4 | monstrous humanoid | any (Izalraan) |
| Iztheptar | 6 | humanoid | any |