Marcus Diadochus

Marcus Diadochus was a Christian writer of the fourth century.
His name is at the head of a "Sermon against the Arians". It was discovered by Johann [Rudolf Wettstein (librarian)|Johann Rudolf Wettstein] in a manuscript codex of St. Athanasius at Basel and published by him at the end of his edition of Origen. Another version of the same work was lent by Galliciolli to Andrea Gallandi and published in the Veterum Patrum Bibliotheca, V. This is the text in Patrologia Graeca.
The sermon quotes and expounds the usual biblical texts, and answers difficulties.
Diadochus, Bishop of Photike in Epirus in the fifth century, is a different person, author of a "Sermon on the Ascension" and of a hundred "Chapters on Spiritual Perfection"; whom Victor Vitensis praises in the prologue of his history of the Vandal persecution. The two are often confused, as Migne does.