Leontius or Leontios (died 705) was a Byzantine emperor.
Leontius or Leontios may also refer to:
- Leontius of Antioch or Leontius the Eunuch (4th century), Patriarch of Antioch 344–358
- Leontius (usurper) (died 488), Byzantine usurper
- Leontius of Byzantium (485–543), Byzantine theological writer
- Leontius II (archbishop of Bordeaux) (r. 542–564)
- Leontius (archbishop of Lyon) (early 6th century)
- Leontius of Jerusalem (6th century), Byzantine theological writer historically confused with Leontius of Byzantium
- Leontios of Neapolis (7th century), Byzantine theological writer
- Łewond (fl. late 8th century), Armenian priest and historian
- Leontius of Damascus (fl. late 8th century), Syrian monk and writer
- Leontius of Alexandria (11th century), Greek Patriarch of Alexandria 1052–1059
- Leontius of Constantinople (died after 1190), Ecumenical Patriarch of Constantinople 1189
- Leontius Pilatus (died 1366), Greek Calabrian scholar
- Saint Leontius of Monemvasia (1377–1452) Greek Orthodox ascetic
- Leontius (Turkevich) (1876–1965), Metropolitan of the North American Diocese of the Russian Orthodox Church 1950–1965
In philosophy[edit]
- Leontius son of Aglaion, an imaginary character in Plato's Republic used to convey a principle.