Man in the Iron Mask

The Man in the Iron Mask (c. 1640 – 19 November 1703) refers to an unidentified prisoner held in various French prisons during the reign of Louis XIV of France.

His face was not revealed, as he wore the eponymous Iron Mask. While many assumptions have been made about his true identity, none have been revealed. Among the most likely theories is that he was an illegitimate son of King Louis, and the mask has supposedly never been found.

Reference

 * Assassin's Creed: Unity - Dead Kings