I have some of those!
Read: Monster Psalms (Matt Guss): 31 standard D&D monster types (goblin, dragon, skeleton, naga, sphinx, …) each with half a dozen tables for unique origins, appearances, motivations, powers, mutations, etc. No stat blocks, but when mechanics come up, it’s clearly generic OSR. Unedited prerelease version, but already has some good bits.
Written: 172.