Encoding the caterwaul from 1979 Fiend Folio. Ye gods, this could be a really vicious monster to sic on a party!
You could be facing a creature with AC:-1, 5 bites every two rounds (1d6) and 2 claw attacks every round (1d4). Then, there's the caterwaul scream. And it's an ambusher, like a bugbear, but better.
Nasty!