Henry I, Duke of Guise

Henry I, Prince of Joinville, Duke of Guise, Count of Eu (31 December 1550 – 23 December 1588), sometimes called Le Balafré (Scarface), was the eldest son of Francis, Duke of Guise, and Anna d'Este. His maternal grandparents were Ercole II d'Este, Duke of Ferrara, and Renée of France. Through his maternal grandfather, he was a descendant of Lucrezia Borgia and Pope Alexander VI.

In 1576 he founded the Catholic League to prevent the heir, King Henry of Navarre, head of the Huguenot movement, from succeeding to the French throne. A key figure in the French Wars of Religion, he was one of the namesakes of the War of the Three Henrys. A powerful opponent of the Queen Mother, Catherine de' Medici, he was assassinated by the bodyguards of her son, King Henry III.

He succeeded his father in 1563 as Duke of Guise and Grand Maître de France. He fought the Turks in Hungary in 1565, and on his return, he became one of the leaders of the Catholic faction in the French Wars of Religion. He fought at the Battle of Saint-Denis in 1567, Battle of Jarnac, successfully defended Poitiers during a siege and fought at the Battle of Moncontour. His love affair with Margaret of Valois in 1570 offended her brother, Charles IX of France and the Queen Mother, Catherine de' Medici, but his marriage to Catherine of Cleves restored his fortunes. Considering the Huguenot leader Admiral Coligny the architect of his father's assassination during the siege of Orléans in 1563, he is a suspect in the murder of the Admiral in August 1572. This was quickly followed by the St. Bartholomew's Day Massacre which took place on the occasion of Margaret's marriage to the Huguenot, Henry of Navarre.