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
OSE Encounter Activity Tables     Any original/official source
Pathfinder 1e Bestiary 1     Pathfinder original/official source
Mythic Monster Manual v1     Pathfinder original/official source
Faerie Bestiary     D&D 5e (no source link)
Beasts Of Legend: Fairy Tale Creatures     D&D 5e (no source link)
Neverland     D&D 5e (no source link)
Monster Ecology Anthology     D&D 5e (no source link)
AD&D Monster Manual     AD&D 1e (no source link)
QUERP Bestiary     QUERP original/official source
Jorgi's Bestiary     Trudvang Chronicles original/official source
Adventures Dark And Deep     Adventures Dark And Deep (no source link)