Looking for Monster-based Class Inspirations for Homebrew

I'm working on a homebrew RPG campaign where my player's classes and races will be Monsters and Creatures. I've only ever played D&D 5E before so many of my campaign's systems will work similarly to that - but I wanted to see if there was any suggestions of other RPGs to research into for inspiration for my various classes.

Interested to see suggestions! I'm very much still in the early phases of developing how it'll play but this world is one inhabited by Classic Universal-style Monsters to Animalfolk.