Undeath

Undeath is a general term for a broad spectrum of energy states which continue to animate a being after life functions have ceased. This can take a variety of forms, ranging from mindless corpses animated by magical force to intelligent beings suffering from curses or necromantic magic. There are even cases of biological pseudo-undeath, when a corpse is manipulated by a biological agent such as a virus, bacteria or plant-form to give it the semblance of life.
Undeath is frowned upon by almost every living mortal civilization. It is considered a disruption to the natural order and it is most practiced by those who consider themselves beyond or outside of normal moral structures. Undead plagues and undead armies have both featured centrally in the plots of many evil beings.
The state of Undeath is most often caused by the school of magic called Necromancy, which directly manipulates life and spiritual energy in relation to the body. Unlike Life or Restoration magic which infuses the body with an outside energy source, Necromancy can also remove, redistribute or even damage life force itself.
Many religions and Deities are particularly opposed to Undeath as it disrupts the ordered progression of life, whether to the aligned realms of Heaven or the Abyss or to re-enter the material world through reincarnation. Paladins, Clerics and other divinely ordained adventurers often have primary duties related to the disruption and destruction of the undead and those who would traffick with them.