The Monsters Know What They're Doing Dungeons And Dragons original/official source
Angry Golem (web) D&D 5e original/official source
OSE Encounter Activity Tables Any original/official source
Pathfinder 1e Bestiary 1 Pathfinder original/official source
Pathfinder 2e Bestiary 1 Pathfinder original/official source
Monster Codex Pathfinder original/official source
Classic Horrors Revisited Pathfinder original/official source
All Sorts Of Critters (web) Pathfinder original/official source
Monster Manual D&D 5e original/official source
Book Of Beautiful Horrors D&D 5e (no source link)
Old Gus: Plantfolk, Undead, And Other Oddities D&D 5e original/official source
Monsters Of The Orient D&D 5e (no source link)
Monster Ecology Anthology D&D 5e (no source link)
Monster Manual D&D 4e (no source link)
Monster Manual 3 D&D 4e (no source link)
Dungeons And Dragons Essentials: Monster Vault D&D 4e (no source link)
D&D 2e Monstrous Manual D&D 2e (no source link)
Scruffy Grognard's Monstrous Manual D&D 2e (no source link)
13th Age Bestiary 13th Age original/official source
Dragonlance Bestiary SAGA (no source link)
Hacklopedia Of Beasts Hackmaster original/official source
Critters, Creatures, & Denizens Dungeon Crawl Classics (no source link)
Monster Guide World Of Warcraft RPG original/official source
Old World Bestiary Warhammer original/official source
Fantasy Age Bestiary Fantasy Age original/official source
Mystara Adversary Compendium I Dragon Age original/official source
Abnormal Undead Any original/official source