A mysterious prisoner in the time of Louis XIV, the Iron Mask and the man who wore it remain a mystery. Many assumptions have been made about his identity although none has been verified. Among the most likely, he could be the illegitimate son of King Louis XIV. While much research has been done, the mask itself has never been found.*
* But we know who it is, right? Too bad he died in the icy waters of the Atlantic after the Titanic sunk. Life's a bitch.