| Name ▼ | Type | CR | Version | Book |
|---|---|---|---|---|
| Seodra | Humanoid | 1/8 | 2014 | Infernal Machine Rebuild |
| Sentinel Marshal | Humanoid | 6 | 2014 | Eberron: Forge of the Artificer |
| Sentient Ochre Jelly | Ooze | 2 | 2014 | Tales from the Yawning Portal: Against the Giants |
| Sentient Gray Ooze | Ooze | 1/2 | 2014 | Tales from the Yawning Portal: Against the Giants |
| Selenelion Twin | Humanoid | 2 | 2014 | The Wild Beyond the Witchlight |
| Sekelok | Humanoid | 9 | 2014 | Tomb of Annihilation |
| Seal | Beast | 0 | 2014 | Icewind Dale: Rime of the Frostmaiden |
| Seahorse | Beast | 0 | 2024 | 2024 Monster Manual |
| Sea Spawn | Monstrosity | 1 | 2014 | Multiple Books (MPMM, VGM) |
| Sea Lion | Monstrosity | 5 | 2014 | Tales from the Yawning Portal: Against the Giants |