Ashburgnul was a title held by the chief Sauronic Priest of the Morannon.
Though a mortal, he had artificially prolonged his life through sorcery - though his status as "alive" seemed debatable - and was several hundred years old.The garrison only referred to him as Ashburgnul (Mor. "Eye of the Dark One") and most but the acolytes kept away from him except during rituals in the chapel.