Pathfinder 1e Bestiary 2 Pathfinder original/official source
Forgotten Foes Pathfinder original/official source
Untamed Wilds D&D 5e original/official source
Critter Compendium D&D 5e original/official source
Monster-A-Day D&D 5e original/official source
Monster Manual 2 D&D 4e (no source link)