A common tool of necromancers, nether mages, and others who are privvy to the arts of the dead and undead
A simple way to a fate most dreadful.
A wet brown sack… FULL OF MAGGOTS!
A planet (or city, valley ect) where those who enter witness protection can escape old age and death itself, so they can live for centuries without aging-provided they maintain their cover perfectly. If they are outed by anyone or ever utter their true name, they age the number of years they have not aged since the day they entered witness protection (which might mean that they age centuries in seconds and crumble into dust and bone.)