The Empress Maria Theresa, Queen of Hungary and Bohemia and Archduchess of Austria from 1740 to 1780.
The only female head of the Habsburg dynasty, she was also Empress of the Holy Roman Empire (1745-1765) AND mother of 16 children. Who says you can't do it all? Her last daughter was Marie Antonia, who became Marie Antoinette, Queen of France, who came to a dramatic end.