The Monsters Know What They're Doing     Dungeons And Dragons 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)
Mythic Monster Manual v1     Pathfinder original/official source
Demons Revisited     Pathfinder original/official source
Mythic Demons     Pathfinder (no source link)
Mythic Menagerie: Demonic Harlots     Pathfinder original/official source
Book Of The Damned: Lords Of Chaos     Pathfinder original/official source
4 Winds Tome Of Monsters     Pathfinder original/official source
Fantastical Creatures     Pathfinder original/official source
Talented Bestiary     Pathfinder original/official source
Monster Manual Expanded v1     D&D 5e original/official source
Monsters And Treasure Of Aihrde     D&D 5e original/official source
Emirikol's Guide To Devils     D&D 5e original/official source
Monster Ecology Anthology     D&D 5e (no source link)
Dragon Magazine     D&D 2e/3e (no source link)
MojoBob (web)     D&D 2e original/official source
AD&D Monster Manual     AD&D 1e (no source link)
Beasties     D&D Basic (no source link)
Monster Guide     World Of Warcraft RPG original/official source
Manual Of Monsters     Amazing Adventures (no source link)
The Fiendish And Unfriendly In Lingusia     Castles And Crusades (no source link)
Harnmaster Gold Bestiary     Harnmaster original/official source
Iron Falcon Handbook Of Monsters     OSR (no source link)
Adventures Dark And Deep     Adventures Dark And Deep (no source link)
Dungeon Fantasy Monsters 2     GURPS 4e original/official source
The Atlantean Bestiary     Any original/official source