Charles I was a monarch of the Hapsburg line who was the last emperor of Austria and king of Hungary. He lost his throne at the end of World War I.

• Emperor, King
  (1887–1922)

James I was a Spanish king best known for fighting the Moors during his reign from 1213-'76. He is also known as James I the Conqueror and James I of Aragon.

• King
  (1208–1276)

Charles I was a king of England, Scotland and Ireland, whose conflicts with parliament and his subjects led to civil war and his execution.

• King
  (1600–1649)

Richard I, better known as "Richard the Lionheart," served as king of England from 1189 to 1199.

• Military Leader, King, Folk Hero
  (1157–1199)

Frederick I was the first king of Prussia. He ruled from 1701 to 1713 and helped establish Prussia’s cultural significance in Europe.

• King
  (1657–1713)

Leopold I was Holy Roman emperor during whose lengthy reign Austria emerged from a series of struggles to become a great European power.

• Emperor
  (1640–1705)

Louis I succeeded his father, Charlemagne, as emperor, serving as ruler of the Franks for 26 years.

• Emperor
  (778–840)

Constantine I was a Roman emperor who ruled early in the 4th century. He was the first Christian emperor and saw the empire begin to become a Christian state.

• General, Religious Figure, Emperor
  (c. 280–337)