Ioannes III (Ancient Greek: Ἰωάννης Γ΄, Iōannēs G΄) may refer to:
- Patriarch John III of Constantinople (died in 577)
- John III Doukas Vatatzes (c. 1192–1254), Byzantine Emperor
- John III Megas Komnenos (c. 1321–1362), Emperor of Trebizond
See also
Topics referred to by the same termThis disambiguation page lists articles about people with the same name. If an internal link led you here, you may wish to change the link to point directly to the intended article.