Demetrius of Magnesia (Ancient Greek: Δημήτριος; 1st century BC) was a Greek grammarian and biographer, and a contemporary of Cicero and Atticus.
A second work of his, which is often referred to, was of an historical and philological nature, and treated of poets and other authors who bore the same name (Greek: Περὶ ὁμωνύμων ποιητῶν καὶ συγγραφέων).
[2] This important work, to judge from what is quoted from it, contained the lives of the persons, and a critical examination of their merits.
For example, Demetrius is cited by Diogenes Laertius as a key source in his biography of the historian Xenophon, providing information about Xenophon that would otherwise be unknown.
Dictionary of Greek and Roman Biography and Mythology.