Constantine I (disambiguation)

Constantine I (272–337), popularly known as Constantine the Great, was a Roman Emperor.

Constantine I may also refer to:
 * Constantine I of Greece (d. 1923)
 * Constantín mac Cináeda (d. 877), also known as Constantine I of Scotland
 * Zara Yaqob (1399–1468), emperor of Ethiopia sometimes known as Constantine I


 * Nobles on the island of Sardinia
 * Constantine I of Arborea, 11th century ruler in Arborea, on the island of Sardinia
 * Constantine I of Cagliari, 11th century ruler


 * Nobles in the Kingdom of Georgia
 * Constantine I of Imereti (d. 1327), king of the Imereti in Georgia
 * Constantine I of Georgia (1369–1412), king of Georgia
 * Constantine I of Kakheti (1567–1605), aka Constantine Khan, King of the Kakheti in Georgia
 * Constantine I, Prince of Mukhrani (fl. 1622 – 1667), a royal of the Bagrationi dynasty of Kartli


 * People in Cilician Armenia
 * Constantine I, Prince of Armenia (1035–1040), second "Lord of the Mountains" of Cilician Armenia
 * Constantine I of Cilicia (fl. 1221–1267), Catholicos of the Armenian Apostolic Church
 * Constantine I, King of Armenia (1278–1310), also sometimes called Constantine III, King of Cilician Armenia (son of Leo II, and brother of Hethum II)


 * Religious leaders
 * Patriarch Constantine I of Constantinople (d. 677), patriarch of Constantinople from 675 to 677
 * Pope Constantine (664–715), Pope from 708 to 715