Lucius Flavius Arrianus 'Xenophon' (ca.

CE 86 - 160), known in English as Arrian, and Arrian of Nicomedia, is a Roman (ethnic Greek) historian, public servant, military commander and philosopher of the 2nd-century Roman period.

Anabasis of Alexander is perhaps his best known work and is generally considered one of the best sources on the campaigns of Alexander the Great, not to be confused with Anabasis, the then best-known work of the Athenian military leader and author Xenophon from the 4th century BCE.

Arrian is also considered as one of the founders of a primarily military-based focus on history.

His other works include Discourses of Epictetus and Indica.

As with other authors of the Second Sophistic, Arrian writes primarily in Attic (Indica is in Herodotus' Ionic dialect, his philosophical works in Koine Greek).