Origin. Alexander was a native of Cotiaeum (Greek Κοτιάειον) — a city in central Phrygia in the Roman province of Asia (modern Kütahya, Turkey). Phrygia in the second century was a Hellenised part of Asia Minor that gave Rome many scholars and philosophers. The standard designation in the sources is Ἀλέξανδρος ὁ Κοτιαεύς (Alexander of Cotiaeum); Marcus in 01-10 briefly calls him ὁ γραμματικός ("the grammarian").

Career: Athens. Before the summons to Rome Alexander taught at Athens. Athens in the second century was the principal centre of Greek education (especially after Hadrian's reforms, which gave Athens state chairs of philosophy). Alexander apparently maintained his own "house" (i.e. school) there, to which pupils came for Greek literature, grammar, and the exegesis of poetic texts (especially Homer). Among his Athenian pupils was Aelius Aristides, who became the principal Greek orator of the Antonine age. Aristides held Alexander in deep reverence and preserved a memory of him to the very death of his teacher.

The summons to Rome. Alexander was summoned to Rome, in all likelihood, in the framework of Marcus's educational programme — after Marcus's adoption by Antoninus Pius in 138. This is a characteristic Antonine practice: leading Greek scholar-teachers were imported to Rome for the instruction of the heirs of the imperial house (the same was done with Apollonius, who was summoned from Athens to Rome in the same years). Capitolinus (SHA Marcus 2.3) enumerates Alexander among Marcus's early teachers.

The principal work: the Commentary on Homer. Rogovin's footnote ¹⁹ to 01-10 mentions "the commentary on the poems of Homer." This is the principal work preserved in Alexander's reputation. The full text has not survived; quotations and mentions in later scholia on the Iliad and Odyssey (the Venice A scholia, the BT scholia, etc.) allow the character to be reconstructed: philological remarks on difficult words, the explication of rare forms, the resolution of text-critical problems, sometimes mythological and cultural-historical comments. This is the typical work of Hellenistic-Roman Homeric philology (in the tradition of Aristarchus, Aristophanes of Byzantium, and Didymus).

Death and the funeral oration of Aelius Aristides. Alexander died in Rome (or, possibly, in Cotiaeum after a return to his native place; the precise place of death is disputed) approximately in the early 150s, in Marcus's lifetime (while Marcus was still Caesar, not emperor). On Alexander's death his former Athenian pupil Aelius Aristides delivered a funeral oration — the "Ἐπιτάφιος εἰς Ἀλέξανδρον" (Aristides, Or. 32 in the numbering of Behr). This is the principal external source on Alexander's biography and character. From this oration may be reconstructed:

• Alexander's devotion to Homeric text-criticism and teaching.
• His reputation as a tactful teacher — the very quality Marcus fixes in 01-10.
• The Athenian period of his teaching and the circle of pupils.
• His high social and cultural standing (Aristides places Alexander in the company of the great Greek teachers of his age).

• 01-10 — the sole direct mention of Alexander in Marcus.
• 01-17 — the thanksgiving to the gods for "having received good teachers"; Alexander implicitly among them.

• SHA Marcus 2.3, 3.5 — mentions of Alexander among Marcus's early teachers; the reference to the commentary on Homer.
• Aelius Aristides, Or. 32 Behr = "Ἐπιτάφιος εἰς Ἀλέξανδρον" — the principal external source; the funeral oration delivered by his former pupil.
• Scholia on the Iliad / Odyssey (the Venetus A scholia, the BT scholia) — quotations and mentions from Alexander's lost Homeric commentary.
• PIR² A 503 — the standard prosopographical entry.
• A. Birley, Marcus Aurelius: A Biography, rev. ed., Routledge, 2000, ch. 3 ("Education") — Alexander in the composition of Marcus's teacherly corps.
• A. S. L. Farquharson, The Meditations of the Emperor Marcus Antoninus, Oxford 1944, vol. II, ad 1.10 — the standard philological commentary.
• R. Hard, Marcus Aurelius: Meditations, OWC, Oxford 2011, notes ad 1.10.
• C. A. Behr, Aelius Aristides and the Sacred Tales, Amsterdam 1968 — the general context and the role of Alexander in the formation of Aristides.
• P. A. Brunt, "Marcus Aurelius in his Meditations," JRS 64 (1974), 1–20 — the general reconstruction of Marcus's educational biography, with discussion of 01-10.