Dracolich. This undead creature results from the necromantic transformation of an evil dragon, always with the help (wanted or not) of at least a 12th-level necromancer. The wizard prepares a receptacle for the dragon's spirit by casting enchant an item and also prepares a necromantic potion. If the dragon consumes the potion (of its own accord, through trickery, or coercion), it dies, and its life force transfers to the enchanted receptacle. Later, the dragon's spirit can reanimate a dead reptilian body. Dracoliches retain all of their abilities and intellect that they possessed in life. In addition to immortality, they gain undead immunities and unique powers.
A dracolich can be an extremely powerful ally for a necromancer, but it is free-willed and not under the wizard's complete domination. The creature must usually be enticed with offerings of treasure in order for it to undertake any mission on behalf of its living caretaker. The Cult of the Dragon, which regards the undead dragon as a semi-divine form, is said to worship the dracoliches they help create.