[quote=HollywoodMole]
Maybe the god of death is the one who ends their natural lifespan?
[/quote]

[quote=BingTheWing]
We could do something like those three old weavers that spin out the creature's life...
[/quote]
How about, the weavers spin out the creature life, and when it's time to die, they tell the god of death. Then, he gets the soon to be deceased person and brings them to the underworld for judgement.