John I of France

John I, called the Posthumous, was the King of France and Navarre, as the posthumous son and successor of Louis X, for the four days he lived in 1316. He is the youngest person to be king of France, the only one to have been king from birth, and the only one to hold the title for his entire life. His reign is the shortest of any undisputed French king. Although considered as a king today, his status was not recognized until chroniclers and historians in later centuries began numbering John II, thereby acknowledging John I's brief reign.