Gayla: A flying manta-ray looking creature found in the north lands. It's cry can put its victims to sleep, after which it will make a low pass, and rain a strength-sapping fluid on it's prey before physically attacking.
Ghost: The spirit of a dead person who for some reason cannot move on, but largely lacks the means by which to directly influence the mortal plane. Trapped in the Spirit Plane adjacent to a fixed, significant area in the physical world, ghosts can sometimes become perceptible, move objects, or make things chilly. If left alone for too long, they lose their inherent will, and end up as environmental special effects.
Ghoul: A form of undead, always a former person. In life, the ghoul was self-absorbed beyond the point of cruelty, the darkest of narcissists. Once risen, they lash out and consume any that frustrate their desires. An an old wives tale states that if you hold your breath until you get what you want, and you asphyxiate, you'll rise as a ghoul. Probably just a fairy tale.
Ghoul, Head: Occasionally, a ghoul will lose enough of its sense of self (either through age or trauma) to transform into one of these monstrosities. A Head Ghoul is literally a man-height head, with outsized but not scale arms and legs. No exotic melee abilities (other than being troll-strong), but the howl of these abominations has the ability to animate any corpses in the vicinity into zombie servants. For better or worse, curse-zombies generated by the core servants are not under the control of the Head Ghoul.
Giant, Moon: An ancient race, rarely seen since the Degenerate Era. Easily thirty feet in height, they appear as massive humans with the heads of owls (Egyptian style). Legends state that they preferred to stay separate from the smaller races, focused on some great cultural duty that was theirs alone. Said to be so in tune with nature and the spirits that a Moon Giant could stand unnoticed in an open pasture.
Giant, Sun: An ancient race, rarely seen since the Degenerate Era. Easily thirty feet in height, they appear as massive humans with the heads of eagles (Egyptian style). Legends state that they didn't care much for, or about the smaller races, and had bizarre abilities even by Divine and Slumbering Era standards.
Glitch: A cat sized vaguely bug-shaped flying creature with a strong Thunder affiliation. They teleport about quite randomly, bite for Electrical and Confusion damage, and occasionally duplicate mid-teleport. The name dates back to the Divine Era: several gods are on record as using it.
Gloombat: Cave dwelling flying mammals with echolocation. Their cries can trigger auditory hallucinations in people, causing them to think they hear their companions saying the most horrible, disheartening, and backstabbing things they have ever imagined. The bats either then feast on the remains of the group melee, or attack the solo survivors.
Goat, Domestic: Sheep with attitudes. Have a tougher digestive system, and can be milked. Also have a penchant for climbing up onto your roof.
Goat, Mountain: Cranky herbivores the size of a human, with strong territorial instincts. Ridiculous climbing ability. Masters of the headbutt.
Goat, Thunder: Ogre sized mountain goats. Purported to be able to walk on clouds. Headbutt generates a thunderclap to stun their opponents, kicks do lightning damage.
Golem: An enchanted, magical construct capable of autonomous movement and performing a number of useful tasks; well, useful as far as their creator was concerned. At no point in Lunistrian history have golems been limited to a humanoid shape. Barring angry mobs with pitchforks and torches, golems invariably outlive their original owners, while the instructions on how to operate them have an irritating habit of becoming lost.
Gorgonne: Resembles a naga with a fully human torso: only the females have snake hair or the petrification gaze. Males of the species are ogre-strong, and can undo the gaze effect of their mates with a touch, usually after shattering the victim. Legends say the gorgonnes lost a war with the humanoid peoples in the early Degenerate Era, and hold a grudge to this day. Normally found in the Burningglass Desert, and adjacent regions.
Grave Corpse: a form of zombie, generated using a lot of power, but not so much in the way of time or finesse. Always created in a graveyard, comprised of whatever is left of the deceased, and a good portion of their grave soil. Irritatingly durable, highly fire resistant, and inevitably, cursed. Generally called forth by the servants of dark gods or demons, and the demonically possessed. Any actual necromancer who calls Grave Corpses up invariably has lost his mind, and is burning his own life force to pull off the stunt.
Gryphon: Expensive military flying mount. Has the front half and wings of a raptor (avian), and the back half of a large feline. Many more breeds exist than the classic eagle/lion mix.
Gryphon, Land: Similar to the standard gryphon: front half flying predator, back half land predator, no wings. Generally larger than their flying cousins. Technically the AD&D Owlbear is in this category.