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 MUD
Discworld MUD is a popular MUD, a text-based online role-playing game, set in the Discworld as depicted in the "Discworld" series of books by Terry Pratchett.