Ioannes I ( el, Ἰωάννης A΄, link=no, "John I") may refer to:
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Patriarch John I of Constantinople (c. 347–407)
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John I Tzimiskes (c. 925–976), Byzantine Emperor
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John I Doukas of Thessaly
John I Doukas ( gr, Ἰωάννης Δούκας, Iōánnēs Doúkas), Latinized as Ducas, was an illegitimate son of Michael II Komnenos Doukas, Despot of Epirus in –1268. After his father's death, he became ruler of Thessaly from to his ow ...
(c. 1240–1289)
See also
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John I (disambiguation)
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Ioannes II (disambiguation) Ioannes II ( el, Ἰωάννης Β΄, "John II") may refer to:
* Patriarch John II of Constantinople (ruled 518–520)
* John II Komnenos (1087–1143), Byzantine emperor
* John II of Trebizond (c. 1262–1297)
* John II Doukas of Thessaly (rule ...
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