Ioannes 458 was bishop of Monembasia; he was the joint addressee with Methodios 1 of a letter from Theodoros 15 (Theodore the Stoudite), written in 817 or 818; he and Methodios 1 were then living in Rome, where they had fled during the persecution under Leo V (Leo 15): Theod. Stud., Ep. 274 (addressed Ἰωάννῃ ἐπισκόπῳ Μονεμβασίας καὶ Μεθοδίῳ ἡγουμένῳ). He is alluded to as the bishop of Monembasia (τοῦ τῆς Μονεμβασίας ἁγίου ἐπισκόπου) in Rome in two other letters of Theodoros 15 written in c. 818: Theod. Stud., Epp. 273, 377. His is not named in a list of bishops of Monembasia in the Synodikon of Orthodoxy: Gouillard, "Synodikon", p. 117, XI, line 11.

(Publishable link for this person: )