Ferdinand III, Holy Roman Emperor (July 13, 1608 – April 2, 1657), ruled February 15, 1637 – 1657.

Eldest son of Emperor Ferdinand II from the house of Habsburg and his first wife, Maria Anna of Bavaria. Made King of Hungary in 1625, King of Bohemia in 1627, and King of the Romans in 1636.

Following the death of Wallenstein in 1634, he was made titular head of the Imperial Army in the Thirty Years War, and later that year joined with his cousin the Cardinal-Infante to defeat the Swedes at Nördlingen.

Leader of the peace party at court, he helped negotiate the Peace of Prague with the Protestant States, especially Saxony in 1635.

He succeeded his father as Holy Roman Emperor in 1637. He hoped to be able to quickly make peace with France and Sweden, but the war dragged on for another 11 years, finally coming to an end with the Peace of Westphalia (Treaty of Münster with France, Treaty of Osnabrück with Sweden) in 1648.

Ferdinand married three times, first to his cousin, the Infanta Maria Anna of Spain, by whom he had two surviving sons: Ferdinand IV, his eldest, who predeceased him, and Leopold, who ultimately succeeded him. After Maria Anna's death in 1646, he married another cousin, Archduchess Maria Leopoldine, daughter of the ruler of Tirol. She died in 1649, and Ferdinand married a third time, to Eleonora Gonzaga, daughter of the Duke of Mantua.