- Roman emperor 324–337: named Constantinople as the new capital; legally sanctioned Christian worship.
- king of Greece 1913–17, 1920–22.
- known as Constantine the Great. Latin name Flavius Valerius Aurelius Constantinus. ?280–337 ad, first Christian Roman emperor (306–337): moved his capital to Byzantium, which he renamed Constantinople (330)
- 1868–1923, king of Greece (1913–17; 1920–22): deposed (1917), recalled by a plebiscite (1920), but forced to abdicate again (1922) after defeat by the Turks
