Ioannes III (, ''Iōannēs G΄'') may refer to: *

Patriarch John III of Constantinople John Scholasticus or Scholastikos. (; 503 – 31 August 577) was patriarch of Constantinople from 12 April 565 until his death on 31 August 577. He is also regarded as a saint of the Eastern Orthodox Church. Life He was born at Sirimis, in t ...

(died in 577) *

John III Doukas Vatatzes John III Doukas Vatatzes, Latinized as Ducas Vatatzes (; 1192 – 3 November 1254), was Emperor of Nicaea from 1221 to 1254. He was succeeded by his son, known as Theodore II Doukas Laskaris. Life John Doukas Vatatzes, born in about 1192 i ...

(c. 1192–1254), Byzantine Emperor *

John III Megas Komnenos John III Megas Komnenos or Grand Comnenus (, ''Iōánnēs Mégas Komnēnós''; – 1362) was emperor of Trebizond from September 4, 1342, to May 3, 1344. He was a son of Emperor Michael of Trebizond (who had reigned for a day in 1341) and Acropo ...

(c. 1321–1362), Emperor of Trebizond

See also