Napoleon II

Napoleon II (Napoléon François Joseph Charles Bonaparte; 20 March 1811 – 22 July 1832) was the disputed Emperor of the French for a few weeks in 1815. He was the son of Emperor Napoleon I and Empress Marie Louise, daughter of Emperor Francis I of Austria. Napoleon II had been Prince Imperial of France and King of Rome since birth. After the fall of his father, he lived the rest of his life in Vienna and was known in the Austrian court as Franz, Duke of Reichstadt for his adult life (from the German version of his second given name, along with a title his grandfather granted him in 1818). He was posthumously given the nickname L’Aiglon (“the Eaglet”) after the popular Edmond Rostand play, L’Aiglon.
When Napoleon I tried to abdicate on 4 April 1814, he said that his son would rule as emperor. However, the coalition victors refused to acknowledge his son as successor, and Napoleon I was forced to abdicate unconditionally some days later. Although Napoleon II never actually ruled France, he was briefly the titular Emperor of the French after the second fall of his father. He lived most of his life in Vienna and died of tuberculosis at the age of 21.
His cousin, Louis-Napoléon Bonaparte, founded the Second French Empire in 1852 and ruled as Emperor Napoleon III.