Ioannes IV

Ioannes IV (Ἰωάννης Δ΄, Iōannēs D΄) may refer to:


 * Patriarch John IV of Constantinople (died in 595)
 * John IV, Archbishop of Ohrid (c. 1088 – 1163/64)
 * John IV Laskaris (1250–c. 1305)
 * John IV Megas Komnenos (c. 1403–1459), emperor of Trebizond