Joseph Fesch, Prince of France (3 January 1763 – 13 May 1839) was a French cardinal and diplomat, Prince of France and a member of the Imperial House of the First French Empire, Peer of France, Roman Prince, and the half-uncle of Napoleon Bonaparte.
Fesch became Archbishop of Lyon in 1802, was named a Cardinal in 1803, became French Ambassador to Rome in 1804, became a French senator and count in 1805, became Grand Almoner of France in 1805, obtained the rank of a sovereign prince in 1806, was named a Prince of France in 1807 (a dignity he shared only with Napoleon's siblings, brother-in-law Joachim Murat and adopted son Eugène de Beauharnais), became a Peer of France in 1815 and was named a Prince of the Papal States by the Pope.
He was a member of the Imperial House as well as of the order of succession to the French imperial throne in accordance with the French constitution of 1804 (Title III, Article 9, "The Imperial Family").
He was Napoleon's most important diplomat in regard to Pope Pius VII, but Napoleon's relationship with his uncle deteriorated as his relationship with the Pope soured.
Nevertheless, Napoleon remained loyal to his uncle.