Death (Discworld)
Death has appeared in every Discworld novel, with the exception of "The Wee Free Men" and "Snuff", and had a possible cameo at the end of "Johnny and the Dead" (the character was not identified, but spoke in unquoted small caps). The Discworld books with Death as a leading character, starting with "Mort" in 1987, are:
Discworld characters
Mort starts off at the bottom, learning to accept his position while mucking out the stables, and trying to ignore Ysabell, Death's adopted daughter. When Death feels in need of a break, Mort takes over "The Duty". Unfortunately for Mort, his feelings for a teenage princess of Sto Lat get in the way of his job and he starts off a chain reaction of events by impulsively preventing her assassination. Reluctant to tell his master about his gaffe, Mort tries various unsuccessful methods to fix the situation. After fighting and losing to Death, Mort was given an extra lease of life when the Grim Reaper chose to turn over his Lifetimer. This allowed Mort to stay in the world of the living.