In typical media they're the epitome of the Evil Sorcerer, showing none of the respect Due to the Dead, using The Dark Arts to create an army of skeletons, zombies, undead animals and undead monsters (or any kind of Undead being) to ravage the countryside or enslave souls of the damned for their own evil and twisted purposes.
Necromancy, the magic of Interrogating the Dead, has been practiced since at least Ancient Greece, where it was known as Necromantia, and probably earlier. A practitioner of a specific kind of Whatevermancy, Necromancers are the masters of the art of death.
