Ioannes VIII (, ''Iōannēs Ē''') may refer to: *

Patriarch John VIII of Constantinople John VIII of Constantinople (; 1010 – 2 August 1075), a native of Trebizond, was a Byzantine intellectual, jurist, and Ecumenical Patriarch of Constantinople from 1064 to 1075. He was the uncle of John Xiphilinus, the Epimator. He is consid ...

(r. 1064–1065) *

John VIII Palaiologos John VIII Palaiologos or Palaeologus (; 18 December 1392 – 31 October 1448) was the penultimate Byzantine emperor. Ruling from 1425 to 1448, he attempted to bring about the reunification of the Orthodox and Catholic churches and prior ...

, Byzantine Emperor (1392–1448)

See also