Imps - little mini demons from the Underworld. Usually break through with a big demon. Feed on torture.
Fungal colonies that reanimate corpses
Cultists that want to summon demons or cthulhu
Goblins with a hob-tree (maybe make kobolds this?)
Attack humans and livestock and store them in their lair for later consumption. Killing the queen (if applicable) destroys the whole colony. Variants without queen should have less members (1/2?) to balance. Variants:
- Spiders (Poison, webs, no queen, live captures)
- Bees (Royal Jelly + Honey, Flight)
- Ants (Acid damage?)
Grief eaters - they magically stay alive by consuming human remains from tombs, thereby desecrating them. Advanced ghoul infestations (and other desecrations) lead to wraith attacks throughout the surrounding area.
???
Origins:
- Spawn from towns with high unrest.
- Failing knight bands can go brigand, depending on leader personality. Good members can defect at this point, and start handing out quests to bring justice to their rogue masters.
Rob villages and travelers for money, food, and other resources. Can demand tribute instead.
Big intelligent carnivores. Need to eat lots of meat to survive. Some eat livestock, but they prefer to eat humans. They make good bandit leaders because they can eat the victims and leave the gold for the bandits. (Note: You could build a lot of monsters on those two sentences as a template) Bandit groups led by ogres are much more bloodthirsty, since they have to kill to keep the Ogre fed. Less murderous ogres might accept livestock as payment for protecting a settlement.