Undead

Undead are those beings, which have died but maintained function either physically or mentally within the physical world of the living. The processes to becoming undead are largely varied, but necromantic energies become the thriving force for all beings that are considered undead.

Necromancy is the school of magic, across all types of Spellcasters, that deal with death, and by extension the undead.

Undead Classification
The undead can be first split into two categories: Corporeal Unead and Incoporeal Undead.Recently a study at the Necromancer's Academy concluded that all undead creatures can also be separated among two further categories: Natural Undead and Engineered Undead.

Physicality
Corporeal undead are those that possess physical form such as Vampires, Zombies, Skeletons. These undead have their "soul" or thriving force bound to the physical vessel, and are vulnerable because of it. These vessels may, or may not be, rejuvenated and rejuvenating (such as vampires), they may freeze as is (such as skeletons), or they may continue to decompose (such as zombies).

Incoporeal undead are those that possess no physical form, and exist in their spiritual form. These undead include the various types of Ghosts, Spectres, or Poltergeists. These are the living force, or soul of an individual continuing to linger in this world.

Origin
Natural undead are those that continue to exist, after their deaths, without any outside influence. These are typically the ghosts that remain to complete their living goals or settle deaths. At times the may regain control of their bodies, but this is typically a result of manufactured undead.

Engineered undead, or manufactured, these are the direct results of the meddlings of a Necromancer. Engineered undead account for the majority of all corporeal undead, and those that are known about at large. This facet of necromancy accounts for the universal disdain of the necromancer as well.

Vampires are an example of an engineered undead, though they are also an example of a prolific undead. Zombies and skeletons are also examples of engineered undead.

Individuality
Most undead do not maintain any intelligence or individual will as they did in life, with only the driving force being preserved in the physical body. This accounts for the majority of engineered undead. They are the undead armies that one hears about.

Those that do retain individuality are often those necromancers that have ungone undead of their own volition. Liches are the best example. The case of vampires also fall into this category.