Couatl

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

Pathfinder 1e Bestiary 1     Pathfinder original/official source

Pathfinder 2e Bestiary 3     Pathfinder original/official source

Mythic Monster Manual v1     Pathfinder original/official source

Mythical Monsters Revisted     Pathfinder (no source link)

Exotic Encounters     Pathfinder original/official source

Latin American Monsters     D&D 5e original/official source

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

Monster Manual 2     D&D 4e (no source link)

MojoBob (web)     D&D 2e original/official source

D&D 2e Monstrous Manual     D&D 2e original/official source

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

Baby Bestiary 1     Any original/official source