Dracopedia Bestiary: An Artist's Guide     Any original/official source
The Monsters Know What They're Doing     Dungeons And Dragons original/official source
Monstrosities     Swords & Wizardry original/official source
Angry Golem (web)     D&D 5e original/official source
Pathfinder 1e Bestiary 1     Pathfinder original/official source
Pathfinder 2e Bestiary 1     Pathfinder (no source link)
All Sorts Of Critters (web)     Pathfinder original/official source
Fantastical Creatures     Pathfinder original/official source
Talented Bestiary     Pathfinder original/official source
Monster Monday (web)     D&D 5e original/official source
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)
Fiend Factory     AD&D 1e (no source link)
Dragonlance Bestiary     SAGA (no source link)
Hacklopedia Of Beasts     Hackmaster original/official source
Monsters Compendium     Heroes Of Adventure (no source link)
Monster Guide     World Of Warcraft RPG original/official source
Frost And Fur     d20 original/official source
Dyval: Hell Unleashed     Rifts (no source link)
Fantasy Age Bestiary     Fantasy Age original/official source
Beyond The Black Sea Bestiary     Beyond The Black Sea (Dark Stars) original/official source
Creature Feature Quarterly