| Name | CR | Type | Environment |
| Lacunal Collector | 11 | undead (android) | any |
| Lacunal Collector, Lacunal Initiate | 1 | undead (android) | any |
| Lawless One | 12 | outsider (extraplanar, chaotic, incorporeal) | any |
| Limbicate | 6 | outsider (extraplanar, incorporeal) | any (the Drift) |
| Limina | 16 | fey | any First World or Material Plane |
| Linyf | 3 | plant | any temperate |
| Liquescence | 2 | ooze (aquatic, water) | any water (Plane of Water) |
| Liquid Arsenate | 7 | ooze | any underground or urban |
| Living Apocalypse | 20 | ooze | any |
| Living Hologram | 8 | construct (incorporeal, technological) | any |
| Lore Guardian | 2 | construct (magical) | any |
| Lovelorn | 4 | undead | any |
| Lucandrian, Albedo Lucandrian | 3 | fey | any lunar |
| Lucandrian, Perigean Lucandrian | 9 | fey | any lunar |
| Luminix | 5 | construct (technological) | any solar |
| Lumocantha, Ancient | 5 | plant | temperate and warm forests |
| Lumocantha | 2 | plant | temperate and warm forests |
| Lurker in Light, Lightweaver | 14 | fey (extraplanar) | urban (extraplanar) |
| Lurker in Light | 5 | fey (extraplanar) | urban (extraplanar) |