Dracolich

In the Dungeons & Dragons roleplaying game, a dracolich is an undead dragon that possesses certain abilities of a lich.

Description
A dracolich resembles a normal, living dragon at first, but as time goes, it ages and begins to partially decompose, eventually coming to resemble a corpse.

Despite its wretched appearance, a dracolich is a very powerful opponent with a correspondingly high challenge rating, due in part to the minions and weapons they tend to possess. Evil chromatic dragons like black, blue and red dragons usually become dracoliches, because of the evil magic involved in their creation; however, rumors spread about other kinds of dragons submitting to the process as well.

Dracoliches are created from evil dragons through powerful necromantic magics. Essentially, it involves the dragon dying and then taking over its own corpse. It also gains a vessel called a phylactery, or soul jar, in which its spirit is stored. The soul continues to exist even after the destruction of the body, and can only be killed by the destruction of the phylactery itself.

Dracoliches in the Forgotten Realms
In the Forgotten Realms campaign setting, an organization known as the Cult of the Dragon is responsible for inventing the method of the dracolich creation. The organization has also created several other undead dragon varieties, as well as other dragon-like monsters including the dracimera (a dragon-chimera) and the mantidrake (a dragon-manticore).

Dracoliches in Greyhawk
The oldest mention of a dracolich (although it simply described as an "undead dragon") belongs to the World of Greyhawk setting, found in the adventure White Plume Mountain. There is a note on the adventure map concerning an undead dragon called Dragotha, formerly consort to Tiamat, who was given his undead powers by the deity Kyuss. It is unknown if other dracoliches exist in Greyhawk.

Dracoliches in other media

 * Vix'thra, the dracolich that was the final boss of the undead section of Neverwinter Nights: Hordes of the Underdark.