Reaper Man - Terry Pratchett

The Discworld is very much like our own - if our own were to consist of a flat planet balanced on the back of four elephants which stand on the back of a giant turtle, that is . . .'Death has to happen. That’s what bein' alive is all about. You're alive, and then you're dead. It can't just stop happening.' But it can. And it has. Death is missing – presumed gone.Which leads to the kind of chaos you always get when an important public service is withdrawn. If Death doesn't come for you, then what are you supposed to do in the meantime? You can't have the undead wandering about like lost souls - there's no telling what might happen! Particularly when they discover that life really is only for the living . . .