Man in the Iron Mask one ever saw his face because it was hidden by a mask of black velvet cloth, the true identity of the prisoner remains a mystery; it has been extensively debated by historians, and various theories have been expounded in numerous books and films. Among the leading theories are those proposed by writer and philosopher Voltaire: he claimed in the second edition of his "Questions sur l'Encyclopédie" (1771) that the prisoner wore a mask made of iron rather than of cloth, and that he was the older, illegitimate brother of Louis XIV. What little is known about the historical Man in
Man in the Iron Mask jailers took – created significant interest in his story and gave birth to many legends. Many theories exist and several books have been written about the case. Some were presented after the existence of the letters was widely known. Still later commentators have presented their own theories, possibly based on embellished versions of the original tale. Theories about his identity popular during his time included that he was a Marshal of France; the English Henry Cromwell, son of Oliver Cromwell; or François, Duke of Beaufort. Later, many people such as Voltaire and Alexandre Dumas suggested other theories about the man