A writhing mass of red tentacles
The RJD2 series virus, affectionately known as The Red Scribble, is the scourge of cyberspace.
"I have seen the beast, tentacled and cruel. Tore out me eye, it did, like pickin’ a plum. It’s cursed, I tell ye, cursed to its cold heart."
-Jerboam the Sailor
Misunderstood and much maligned, the Hek is a traveller who dreads violence. If it only understood the violence it caused.
The local band of 'nasties' (goblins / orcs / whatever) lives in relative peace with the local population.
Along come the PCs and go through their usual heroic monster bashing routine, wiping out the nasties and pinching all their stuff, then continue on their way.
Problem is, they don't kill ALL he nasties. The survivors want revenge and, after spending a few months recovering, start to take it in their own inimitable style (which is not unlike that of the PCs come to think of it).
Next time the PCs are in the area they find themselves VERY unpopular with the townsfolk.