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 2     Pathfinder original/official source
Pathfinder 2e Bestiary 3     Pathfinder original/official source
Monstrous Compendium: Al-Qadim     D&D 2e original/official source
Hacklopedia Of Beasts     Hackmaster original/official source