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
Pathfinder 2e Bestiary 1     Pathfinder original/official source
Pathfinder 2e Bestiary 2     Pathfinder original/official source
Mythic Monster Manual v2     Pathfinder original/official source
Talented Bestiary     Pathfinder original/official source
Critter Cache: Animals And Beasts     D&D 4e original/official source
MojoBob (web)     D&D 2e original/official source
D&D 2e Monstrous Manual     D&D 2e (no source link)
Scruffy Grognard's Monstrous Manual     D&D 2e (no source link)
Hacklopedia Of Beasts     Hackmaster original/official source
Critters, Creatures, & Denizens     Dungeon Crawl Classics (no source link)
Arrows Of Indra     Arrows Of Indra (no source link)
Adventures Dark And Deep     Adventures Dark And Deep (no source link)