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)
Fans launched a tongue-in-cheek petition on Change.org, requesting for Death to return Pratchett to life because "Terry Pratchett turned Death from a figure of hate into a much loved and sometimes welcomed character. No-one else cared about you Death. You owe him!"