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:
Reaper Man
When humankind finally thinks of a New Death, one with a crown and without any humanity or human face, it goes to take Bill Door. Death/Door, having planned for this moment for some time, outwits and destroys it. Having defeated the New Death, Death absorbs the other Deaths back into him, with the exception of the Death of Rats (and ultimately, the Death of Fleas). Death confronts Azrael, the Death of the Universe, and states that the Deaths have to care or they do not exist and there is nothing but Oblivion, which must also end some time.