There are many BRP monster books.
This one is a good free one.
https://the-eye.eu/public/Books/rpg.rem.uz/_Collections/Bestiaries/Bestiary 5/BaSIC Bestiary.pdf https://fdocuments.in/document/a-basic-bestiary-rpgremuz-of-cthulhumiscbasic-roleplayingbrp-a-praying.html