| Name | CR | Type | Environment |
| Gammenore | 8 | magical beast (cold) | any cold (Triaxus) |
| Garaggakal | 5 | outsider (extraplanar) | any (the Drift) |
| Garaggakal, Garaggakal Polymath | 14 | outsider (extraplanar) | any (the Drift) |
| Gatecrasher | 10 | undead | any |
| Gathol | 3 | humanoid (gathol) | any |
| Genereaver | 10 | aberration | any |
| Genesis Wraith | 17 | undead (incorporeal) | any vacuum |
| Genie, Djinni | 5 | outsider (air, extraplanar) | any (Plane of Air) |
| Genie, Efreeti | 8 | outsider (extraplanar, fire) | any (Plane of Fire) |
| Genie, Janni | 4 | outsider (native) | any |
| Genie, Marid | 9 | outsider (aquatic, extraplanar, water) | any (Plane of Water) |
| Genie, Shaitan | 7 | outsider (earth, extraplanar) | any (Plane of Earth) |
| Ghibrani | 3 | humanoid (ghibrani) | any (Elytrio) |
| Ghigorda | 18 | magical beast | any (Daimalko) |
| Ghoran, Ghoran Flora-Shaper | 6 | plant | any |
| Ghoran, Ghoran World-Tamer | 1 | plant | any |
| Ghost | 7 | undead (incorporeal) | any |
| Ghoul | 1 | undead | any |
| Ghoul, Ghoul Shock Trooper | 11 | undead | any |
| Ghul | 5 | undead (shapechanger) | any |
| Giant Jelly | 5 | animal (aquatic) | any water (Entha) |
| Giant, Eclipse | 19 | humanoid (giant) | any |
| Giant, Moon Giant | 15 | humanoid (giant) | any lunar |
| Giant, Shadow | 13 | humanoid (extraplanar, giant) | any (Shadow Plane) |
| Glacial Borer | 6 | animal | any cold (Verces) |
| Glaiad | 6 | fey | space (planetary rings) |
| Glass Serpent | 5 | magical beast | any (Eox) |
| Glitch Dog | 4 | magical beast | any |
| Gloomwing | 4 | outsider (extraplanar) | any land or sky (Shadow Plane) |
| Goblin (Space), Space Goblin Honchohead | 2 | humanoid (goblinoid) | any |
| Goblin (Space), Space Goblin Zaperator | 1/3 | humanoid (goblinoid) | any |
| Golem, Abysium Golem | 12 | construct (magical, technological) | any |
| Golem, Cybernetic Golem | 8 | construct (magical, technological) | any |
| Golem, Junk | 4 | construct (magical, technological) | any |
| Golem, Nanotech Golem | 14 | construct (magical, technological) | any |
| Golem, Neutronium Golem | 6 | construct (magical, technological) | any |
| Gravite | 7 | outsider (native) | vacuum |
| Gray | 4 | humanoid (gray) | any |
| Gray Bounder | 4 | aberration (gray) | any |
| Gray Goo | 14 | construct (swarm, technological) | any |
| Gray Shell | 13 | humanoid (gray) | any |
| Gremlin, Computer Glitch Gremlin | 1/2 | fey | any |
| Gremlin, Drikluz | 1/2 | fey | any |
| Gremlin, Hobkins Gremlin | 1/2 | fey | any |
| Gremlin, Hobkins Gremlin Malefactor | 4 | fey | any |
| Gremlin, Ship Glitch Gremlin | 1 | fey | any or vacuum |
| Gremlin, Vaigruuk | 2 | fey | any |
| Grioth, Eclipse Seer | 6 | monstrous humanoid | any |
| Grioth | 1 | monstrous humanoid | any |
| Guardian Rhino | 14 | monstrous humanoid (shapechanger) | any ( Jatembe Park) |
| Guides, Captains Club Guide | 13 | magical beast | — |
| Guides, Courier | 7 | humanoid (ryphorian) | — |
| Guides, Personal Concierge | 3 | monstrous humanoid | — |
| Guides, Stowalong | 9 | humanoid (worlanisi) | — |