Maria Theresa (1717-1780) was the eldest daughter of Elisabeth Christine of Brunswick-Wolfenbuttel and Charles VI, Holy Roman Emperor, and succeded to the throne of Austria as a result of the death in infancy of her only brother. She married Francis I, Duke of Lorraine (1708-1765) in 1736 and in the following year Francis became the Grand Duke of Tuscany on the death of the last Medici Duke. However, Maria Theresa's position was disputed, sparking the War of Austrian Succession in 1740 and the throne was subsequently claimed by Charles VII. When Charles died in 1745 Maria Theresa re-claimed the Imperial Crown of the Holy Roman Empire for her husband, though she continued as de facto ruler of the Empire, establishing herself as a key figure in the politics of Europe in the 18th century.
Among her sixteen children, her youngest daughter Maria-Antonia (b.1755) married Louis XVI of France and became better known as Marie-Antoinette.