Dracopedia Bestiary: An Artist's Guide     Any original/official source
The Monsters Know What They're Doing     Dungeons And Dragons 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
Mythic Monster Manual v2     Pathfinder original/official source
Monster Manual     D&D 5e original/official source
Monster Monday (web)     D&D 5e original/official source
Monster Ecology Anthology     D&D 5e (no source link)
Monster Manual     D&D 4e (no source link)
D&D 2e Monstrous Manual     D&D 2e original/official source
Scruffy Grognard's Monstrous Manual     D&D 2e (no source link)
AD&D Monster Manual     AD&D 1e (no source link)
Dragonlance Bestiary     SAGA (no source link)
Hacklopedia Of Beasts     Hackmaster original/official source
Monsters Compendium     Heroes Of Adventure (no source link)
Warlords Of The Accordlands: Monsters And Lairs     d20 original/official source