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
Dungeon Denizens Revisited     Pathfinder original/official source
All Sorts Of Critters (web)     Pathfinder original/official source
Monster Manual     D&D 5e original/official source
Monster Ecology Anthology     D&D 5e (no source link)
Monster Manual     D&D 4e (no source link)
Dungeons And Dragons Essentials: Monster Vault     D&D 4e (no source link)
Dragon Magazine     D&D 2e/3e (no source link)
AD&D Monster Manual     AD&D 1e (no source link)
13th Age Bestiary     13th Age original/official source
Dragonlance Bestiary     SAGA (no source link)
Baby Bestiary 2     Any original/official source