Theophanes 18 was the author of the chronicle known as the Chronographia of Theophanes Homologetes.

Theophanes 18 was born c. 760 (he was aged fifty-three at the start of the reign of the emperor Leo V, Leo 15) and was the son of Isaakios 12 (droungarios of Aigaion Pelagos) and of Theodote 5; under the emperor Leo IV (Leo 4; 775/780), after the death of his mother (Theodote 5), he became a strator and was sent on a misson to Kyzikos; later he became a spatharios: Vita Theod. Conf. (BHG 1787z) 10, Vita Theoph. Conf. (BHG 1789) 7, 8, Vita Theoph. Conf. (BHG 1791) 390. Husband of Megalo 1 (daughter of a patrikios, Leo 271); after the death of Leo IV (Leo 4) he became first a monk and then a hegoumenos: Vita Theoph. Conf. (BHG 1787z) 6, p. 4, 11-14, pp. 7-10, 20, p. 15, 21, p. 15, Vita Theoph. Conf. (BHG 1788) 290, cap. 2, 291, cap. 3, Vita Theoph. Conf. (BHG 1789) 4, 32-6, 32, Vita Theoph. Conf. (1791) 390, 4-6, 391, 11, 392, 3-11, Theod. Stud., Laud. Theoph. (BHG 1792b) 20, 29-31, 3; 31-33; 23, 10-15, Synax. Theoph. Conf. (BHG 1792e) 41, 16-42, 15.

Theophanes 18 was founder of the monastery of Megas Agros on the mountain of Sigriane: Nicetas, Vita Ignatii 500B (τὸν τῆς καλουμένης Σιγριανῆς λέγω μονῆς οἰκιστήν). In 815 he was the hegoumenos of the monastery of the Agros; he was observed through spiritual means, apparently performing some ceremony (θυμιάμασί τε καὶ λάμπασι δεξιούμενον), by the patriarch Nikephoros 2 from the boat in which the latter was sailing into exile; when asked by a fellow-traveller who the man was, Nikephoros 2 foretold that Theophanes 18 would die a confessor for his faith ("τῷ ὁμολογητῇ" φάναι "Θεοφάνει" προφήτιδι γλώττῃ "μονῇ προεστῶτι τοῦ Ἀγροῦ"): Theoph. Cont. I 18 (pp. 29-30). Hegoumenos of the monastery of Megas Agros, he knew through the working of the spirit that Nikephoros 2 was passing on his way to exile and performed ceremonies for him, although neither could see the other; similarly Nikephoros 2 responded and anticipated his fate by naming him Confessor to the ship's crew: Zon. XV 19. 37-39 (ὁ δὲ τοῦ μεγάλου Ἀγροῦ καθηγούμενος ὁ ὁμολογητὴς Θεοφάνης), Genesius I 14, Scyl., 15-16. He was visited by Ignatios 1 when the latter was very young but already a monk (therefore between 813 and 817/818, when Theophanes 18 died) and was said (ὡς λόγος) to have blessed him as a future patriarch of Constantinople: Nicetas, Vita Ignatii 500B. Head of the Agros monastery and a Confessor (ὃν ὁμολογητὴς Θεοφάνης καὶ τοῦ Ἀγροῦ ἡγούμενος), Theophanes 18 composed an historical work which continued the chronicle of George Synkellos (Georgios 137); he began at the point where Georgios 137 ended, viz. the reigns of the emperors Maximian and Maximin (Galerius and Maximin Daia), and ended with the death of the emperor Nikephoros 8: Scyl.,, proem., p. 3. Described as a great performer of works of piety and of prodigies and miracles: Nicetas, Vita Ignatii 500B (Θεοφάνην ἐκεῖνον τὸν μέγαν ἐν τοῖς ὑπὲρ εὐσεβείας ἀγῶσι, καὶ πολὺν ἐν σημείοις καὶ θαύμασι). He was buried at his monastery of Sigriane: Sabas, Vita Ioannicii 31 (πρὸς τὴν Σιγριανὴν μονὴν τοῦ ἁγίου Θεοφάνους, τὴν ἐπονομαζομένην Ἀγρόν), cf. Petrus, Vita Ioannicii 37 (the monastery and the tomb are described as belonging to Isaac the Great, but the story, of a visit by Ioannikios 2, is the same as that told by Sabas 1). He is described as the author of verses describing how the patriarch Theodotos 2 manoeuvred the emperor Leo V (Leo 15) into supporting iconoclasm (ὡς καὶ παρὰ τοῦ μακαρίτου Θεοφάνους καὶ ὁμολογητοῦ ταῦτα δι' ἐμμέτρου ποιήσεως ἐστηλίτευτο): Genesius I 13.

Theophanes 18 was the addressee of two letters from Theodoros 15 (Theodore the Stoudite): Theod. Stud., Ep. 214 (addressed Θεοφάνῃ ἡγουμένῳ τοῦ Ἀγροῦ), 291 (addressed Θεοφάνῃ ἡγουμένῳ καὶ ὁμολογητῇ). He is mentioned in a number of other letters from Theodoros 15: Theod. Stud., Ep. 292, 311, 319, 323, 333, 396, 443, 487.

Author of a chronicle, in which he wrote about the Prophet Muhammad: Const. Porph., DAI 17, 1. He founded the monastery of Megas Agros: Const. Porph., DAI 22, 77ff. He was allegedly the maternal uncle (μητρόθειος) of the emperor Constantine Porphyrogenitus: Const. Porph., DAI 22, 77ff.

Theophanes 18 died on 12 March: Synax. Eccl. Const. 529-531, Menologium ed. Latyshev 348-349.

Styled τοῦ ὁσιωτάτου ἡγουμένου τοῦ Μεγάλου Ἀγροῦ, Theophanes 18 is included among those acclaimed for their support of icons in the Synodikon of Orthodoxy: Gouillard, "Synodikon", p. 53, line 133.

(Publishable link for this person: )