Death

Again I'm talking about Death, but this time it is about one of the Four Horsmen.
He is as old as world and god himself, been always there to reap souls of fallen. In souls of Fallen I mean even the Angels who have lost their wings and fallen to Earth for treason against their brothers and sisters. But Death reaps everything else too: animals, humans and even plants. He is just a Grim Reaper, because people are getting their numbers higher and higher is work gets very hard. So he called up for lost souls who had nothing else to do and asked them to collect souls of the fallen and dying ones.
Now he rests in Hell with his brothers: War, Pestilence and Famine. Only time him to leave Hell is when his brothers leave the Hell to for some little time. He rides out on pale steed, depending from era it can be a pale horse or a white Cadilac. It only happens when the apocalypse starts, so till that you don't have to be scared by meeting them. They wouldn't be walking on Earth before Apocalypse.