Henry III (born Alexandre Édouard de France, Polish: Henryk Walezy, Lithuanian: Henrikas Valua) was a monarch of the House of Valois who was elected the monarch of the Polish-Lithuanian Commonwealth from 1573 to 1575 and ruled as King of France from 1574 until his death. He was the last French monarch of the Valois dynasty.
As the fourth son of King Henry II of France and Catherine de' Medici, Henry was not expected to assume the throne of France. He was thus a good candidate for the vacant Polish throne, and he was elected with the dual titles King of Poland and Grand Duke of Lithuania.
Henry's rule over Poland was brief, but notable. The Henrician Articles he signed into law accepting the Polish throne established Poland as an elective monarchy subject to free election by the Polish nobility. Of his three older brothers, two would live long enough to ascend the French throne, but both died young and without a legitimate male heir. He abandoned Poland upon receiving word that he had inherited the throne of France at the age of 22.
The kingdom of France was at the time plagued by the Wars of Religion, and Henry's authority was undermined by violent political parties funded by foreign powers: the Catholic League (supported by Spain), the Protestant Huguenots (supported by England and the Dutch) and the Malcontents, led by Henry's own brother, the Duke of Alençon, which was a party of Catholic and Protestant aristocrats who jointly opposed the absolutist ambitions of the king. Henry III was himself a politique, arguing that a strong and religiously tolerant monarchy would save France from collapse.
After the death of Henry's younger brother Francis, Duke of Anjou, and when it became apparent that Henry would not produce an heir, the Wars of Religion grew into a succession crisis that resulted in a war known as the War of the Three Henrys. Henry III's legitimate heir was his distant cousin Henry, King of Navarre, a Protestant. The Catholic League, led by Henry I, Duke of Guise, sought to exclude Protestants from the succession and championed the Catholic Charles, Cardinal of Bourbon, as Henry III's heir.
In 1589, Jacques Clément, a Catholic fanatic, murdered Henry III, who was succeeded by the King of Navarre who, as Henry IV, would assume the throne of France after converting to Catholicism, and become the first French king of the House of Bourbon.