Underground Monsters
in Old-School Essentials Classic Fantasy
31 monsters
- Ape, White - Albino, herbivorous, gorilla-like apes that live in caves and emerge at night to forage
- Arachnid, Giant Tarantella - Huge, hairy, nocturnal arachnid carnivores with large heads and mandibles and 10 legs
- Basilisk - 10' long, serpentine lizards. Unintelligent, but highly magical
- Black Pudding - Amorphous creature that lives only to eat, scouring underground areas for organic matter
- Black Widow - 6' long, black spiders with a red hourglass pattern on their abdomens
- Carrion Crawler - 9' long, 3' high, many-legged, segmented worms with a ring of 2' long tentacles around their mouths
- Cave Bear - Ferocious, 15' tall grizzly bears found in caves and Lost World settings
- Centipede, Giant - Larger versions of normal centipedes, 2 to 3 feet long, fast-moving predatory venomous arthropods
- Cyclops - 20' tall humanoids with a single, central eye
- Fire Beetle - 2½' long. Commonly found underground
- Gelatinous Cube - Nearly transparent cube that travels dungeon corridors absorbing carrion, creatures, and trash
- Giant Ferret - 3' long ferrets that hunt giant rats in their burrows
- Giant Shrew - Brown-furred, mole-like, insectivores with long snouts. Dwell underground; skilled burrowers.
- Giant Weasel - 8' to 9' long, vicious, predatory mammals with rich fur of brown, gold, or white
- Green Slime - Dripping, green slime that clings to walls and ceilings
- Grey Ooze - Slimy horrors that lurk on stone surfaces or among boulders
- Killer Bee - Giant (1' long) bees of aggressive temperament. Build hives underground.
- Kobold - Small, dog-faced reptilian humanoids
- Minotaur - Huge bull-headed humanoid monsters
- Neanderthal - Squat, powerful, primitive demihumans with ape-like faces
- Ochre Jelly - Giant, ochre amoeboids
- Oil Beetle - 3' long, burrowing beetles sometimes encountered below ground
- Purple Worm - Gigantic subterranean monsters with poisonous stingers
- Rock Cricket - 2–3' long, herbivorous, giant crickets that dwell in caverns
- Rust Monster - Strange monster built like a huge turtle with insectoid head and feather-like antennae
- Shrieker - Large, semi-mobile fungus that wails loudly when approached or threatened
- Skeleton - Mindless undead created to guard tombs or serve their creator
- Stone Giant - 14' tall humanoids with stone-like, grey skin
- Thoul - Magical monstrosities that look like hobgoblins (except on close inspection), but combine the powers of ghouls and trolls
- Troglodyte - Intelligent, reptilian humanoids with agile hands, long legs, short tails, and spiky combs on their heads and arms
- Yellow Mould - Deadly fungus that covers walls, ceilings, and other surfaces