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)
When Death goes missing in "Soul Music", Albert tries to find him on the Disc, but gets robbed and his life-timer (hourglass of life) is broken. After this incident, Albert has approximately 34 seconds left, and thus cannot return to the world of the living anymore, as Death cannot make his life longer. The remaining sand is now kept in a bottle in Albert's bedroom. Albert is able to temporarily return to the Discworld during the events of "Hogfather", although in this instance he merely inhabits the pseudo-reality created for the Hogfather to allow him to travel around the entire world in a single night, and hence is not actually "in" the world, strictly-speaking.