Xhamathaxanor

Xhamathaxanor was a Beholder  from the @Real. It found itself fascinated by the corrupting powers of The Rending, so it journeyed up from the Underdark through the ancient Dragonborn city of Mahakazor in the Desolation of Azmartheon. When the Shadow Dragons Umbrazhalanoth and Skyalokanara dragged part of Mahakazor into the Shadowfell, Xhamathaxanor became fascinated by the necrotic energies that were left behind.

Xhamathaxanor slowly began to lure other, less powerful beholders into its lair. It would then kill them, mummify them, and use the energies of the Shadowfell to reanimate them as Undead. He used them to enslave all those who stop for shelter in the ruins of Mahakazor.

Ultimately, Xhamathaxanor met his end at the hands of the Fire Wasps, who led the dragonborn in the liberation of their city. He did slay three of their number before falling himself, although all were returned to life by the powers of Brother Natharios.