Manticore

Dracopedia Bestiary: An Artist's Guide     Any original/official source

The Monsters Know What They're Doing     Dungeons And Dragons original/official source

Angry Golem (web)     D&D 5e original/official source

Atlas Animalia     Any 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

Exotic Encounters     Pathfinder original/official source

Mythic Adventures     Pathfinder original/official source

Monster Manual     D&D 5e original/official source

Kobold Press Creature Codex     D&D 5e original/official source

Flee, Mortals     D&D 5e (no source link)

Monster Ecology Anthology     D&D 5e (no source link)

Monster Manual     D&D 4e (no source link)

Dungeons And Dragons Essentials: Monster Vault     D&D 4e (no source link)

Scruffy Grognard's Monstrous Manual     D&D 2e (no source link)

AD&D Monster Manual     AD&D 1e (no source link)

13th Age Bestiary     13th Age original/official source

Dragonlance Bestiary     SAGA (no source link)

Monsters Compendium     Heroes Of Adventure (no source link)

Old World Bestiary     Warhammer original/official source

Warlords Of The Accordlands: Monsters And Lairs     d20 original/official source

QUERP Bestiary     QUERP original/official source

The Monster Overhaul     OSR (no source link)

The Atlantean Bestiary     Any original/official source

Lairs And Encounters     Adventurer, Conqueror, King (no source link)

Baby Bestiary 1     Any original/official source