In The Light Fantastic, Rincewind overhears Twoflower teaching the Four Horsemen of the Apocalypse, (Death, Famine, Pestilence and War) how to play bridge.
Ysabell is the adopted daughter of Death, who saved her as a baby when her parents were killed in the Great Nef desert (no explanation has been given as to why he did this; Ysabell said that "He didn't feel sorry for me, he never feels anything..