@deidungeon Not a particular favourite, but I like taking regular monsters and fleshing them out.
Ran tower dungeon with a family of ‘ghouls’ in various states of transformation recently, and it was a lot of fun. Grandmother fully transformed kept caged in the entry, uncles partially transformed and kept from the hearth room, half-elf mother partially affected, and unaffected daughter who was kept in the tower top hearth room.
Fighting Fantasy Russ Nicholson really inspired this vibe.