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:
Death (Discworld)
The Death of Rats, also known as the Grim Squeaker, is not, strictly speaking, a personification in his own right but rather an aspect of Death allowed an independent existence. His purpose is to usher on the souls of dead rodents, as well as assisting Death in other ways. His jurisdiction also seems to cover certain kinds of "ratty" humans, such as Mr. Clete in "Soul Music", Mr. Pin in "The Truth", and Mr. Pounder in "Maskerade".