Carasso, from Ultima Underworld
While searching through the eighth and final level of the Abyss in Ultima Underworld I, the Avatar heard someone in a room in the eastern portion of the level. Smashing the door open, the Avatar found the half-starved Carasson, who'd been locked into this cell by Tyball. After giving him food, Carasso told how he'd found the bones of a powerful wizard (Garamon) to the west. He also gave the Avatar a key that would open the door to a path that led to the chamber of virtue, but warned of a powerful Stone Golem, before leaving for the upper levels.
Most likely he was saved by Garamon, when the volcano erupted.