Monstrosities     Swords & Wizardry original/official source
Pathfinder 1e Bestiary 1     Pathfinder original/official source
Fey Revisted     Pathfinder original/official source
Fantastical Creatures     Pathfinder original/official source
Fey Folio     D&D 5e original/official source
Monster Manual 3     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 2     13th Age (no source link)
Monsters Compendium     Heroes Of Adventure (no source link)
QUERP Bestiary     QUERP original/official source
Jorgi's Bestiary     Trudvang Chronicles original/official source
Fantasy Age Bestiary     Fantasy Age original/official source
Monsters, Minions, And Marauders     Hero System original/official source
Terrible Beauty     Shadow Of The Demon Lord (no source link)
D6 Fantasy Creatures     d6 (no source link)
The Atlantean Bestiary     Any original/official source