"I'm lookin' for the man that shot mah paw!" as the Western stereotype goes.
As much killing as the typical party goes, they had to leave behind some survivors. I don't mean from the actual combats, but from the families of the deceased.
It doesn't matter how evil someone is, if you look hard enough, you'll find they were someone else's beloved. Even Jeff Dahmer's parents were sad to hear he died, after all.
This is the amazing thing. The campaign is part 2 of a game I ran a couple years ago, which ended with this awesome climax:
http://www.enworld.org/forum/general-rpg-discussion/197996-how-end-world.html#post3564293
The total death count, since we picked the game back up in January:
* 1 ogre whom the party chased down after driving off the invaders. Four ogres had kidnapped some townsfolk before escaping, and the PCs only killed one of them because they had to.
* A few sabertooth tiger kittens were collateral damage when the PCs tried to scare off their mom who was attacking an innocent bystander. They've also killed some undead, some bats, an a twisted half-metal beast. None of them sentient.
* A Vrock who was serving as the minion of one of the ogre leaders. The fight also involved 3 ogres, whom the PCs spared. They even enlisted the ogre leader they'd beaten as an ally.
* One PC took revenge against an ogre who'd attacked his mom, and they both died in the process. Then they were fused together by magic and brought back to life as one being.
* In the last session, an enemy used an area attack on the party, which a PC redirected, and that ended up killing one of the enemies. The rest of the enemies surrendered when the PCs knocked out their leader and ordered them to stand down.
The kill count is insanely low by normal adventurer standards. Part of this is because one player consciously decided to make a 'moral' character, to show how adventuring would be if you couldn't just kill your way to victory. Still, yeah, they do have people who are disgruntled at them, but they have enough support from the people who give those folks orders that they've been safe. Another reason for me to shoo the PCs to some place new.