Ionu's Compendium of Strange Creatures     D&D 5e original/official source
Monsters Of The Infinite Planes     D&D 5e original/official source
Scruffy Grognard's Monstrous Manual     D&D 2e (no source link)
AD&D Monster Manual     AD&D 1e (no source link)
The Monster Overhaul     OSR (no source link)