Death

Okay, so... I chose this answer because I play with aging off and I don't want my Sims to age unless I choose to age them. So I've never had a Sim die of "natural causes". That doesn't mean I don't let them die otherwise, though. I like to leave their fates up to chance in the game and roll with it if it happens. Despite my love for "darker" gameplay, I don't actually seek to murder my Sims on purpose. Usually. I do have certain Sims created to "become" specific Ghost types one day because I just love to play various Occults and we can't create Ghosts in CAS. But it's really surprising how easy it is to actually avoid death without really trying. That's okay though, I put a lot of work into my Sims because I want to play them, not lose them to death. But just knowing there's a plethora of ways they could meet their demise if I'm not paying attention is good enough for me.