Terry Pratchett – Reaper Man (1991)
Alone of all the creatures in the world, trolls believe that all living things go through Time backward. If the past is visible and the future is hidden, they say, then it means you must be facing the wrong way. Everything alive is going through life back to front. And this is a very interesting idea, considering it was invented by a race who spend most of their time hitting one another on the head with rocks.