Lost Mines of Phandelver
The Flameskull formerly known as Illarios Pezz
Was a wizard. Now a flaming skull. Freed by the party.
Illarios was once a wizard who worked in Wave Echo Cave at the time of the Orcish invasion. Unknown to him, his mentor and father figure betrayed Illarios and turned him into a Flameskull so that he might better defend the cave.
Illario survived the ordeal and would guard the mine for centuries to come until he was discovered by the Dragon’s Fang. Diplomanced by Jack Ninestrings, Illario was freed from his servitude to the mine. Where he now wanders, no one knows.