Angry Golem (web)     D&D 5e original/official source
Pathfinder 1e Bestiary 4     Pathfinder original/official source
Pathfinder 2e Bestiary 3     Pathfinder original/official source
Critter Cache: Animals And Beasts     D&D 4e original/official source
Hacklopedia Of Beasts     Hackmaster original/official source
Critters, Creatures, & Denizens     Dungeon Crawl Classics (no source link)