Constantine I.
Constantine I designates the following people:
- Constantine the Great (* between 272 and 285; † 337), Roman emperor
- Constantine I (Patriarch) , Patriarch of Constantinople
- Constantine I (Pope) († 715), Pope
- Constantine I (Scotland) (836–877), Scottish King
- Constantine I (Armenia) , Armenian prince
- Constantine I (West Georgia) , West Georgian King
- Constantine I , throne name of Zara Yaqob (1399–1468), Ethiopian emperor
- Constantine I (Georgia) , Georgian King
- Constantine I (Kakheti) , Kakheti king
- Constantine I (Greece) (1868–1923), Greek king