Since I'm in a quoting mood today, and the text is excessively relevant, Faces of Evil page 42:
"When a mortal has devoted his life to chaos and evil dies, he becomes a petitioner, and his spirit wends its way to the Outer Plane that most closely matches the essence of his former being: the Abyss. If, in life, the petitioner worshipped a particular Abyssal deity, he ends up in that power's realm and is transformed into a shape of the god's choosing (perhaps even his original form).
If, on the other hand, the mortal did not pledge his life to any one power, his spirit becomes a disgusting larva, which is still considered a petitioner. The new larva appears in the Mountain of Woe (the 400th layer of the Abyss), where it is judged by pompous nalfeshnee according to the following guidelines:
· Spirits with little promise become manes, fit only as food or supremely expendable soldiers. Like larvae, manes are still petitioners.
· Spirits that seem sufficiently evil and malleable become dretches - honest-to-goodness members of the fiendish race.
· Especially proud spirits that need to learn humility - and humiliation - become rutterkin, mightier than either manes or dretches but also more reviled."
"You - manes. You - rutterkin. You - dretch. You - dinner." - Magistrate Oozewart, nalfeshnee lord, judging petitioners.