Nobody knows the identity or background of the Roman author Q. Curtius Rufus, or when he wrote his History of Alexander the Great. This text along with Arrian’s Anabasis, Plutarch’s Life of Alexander, Diodorus Siculus Book 17 and Justin’s Epitome of Trogus Books 11–12 and the Metz Epitome is one of the main ancient sources on the reign and campaigns of the Macedonian conqueror. This chapter surveys current thinking on Curtius’ history, including issues like the historian’s probable sources, his literary structure, intertexuality and his characterization of Alexander. In particular the chapter explores the historian’s excursuses – in which he appears to be speaking in propria persona on Alexander’s personality as well as his portrayal of Alexander’s relationships with women, including the Athenian courtesan, Thais ,and the Amazon queen, Thalestris, and especially, the Persian queen, Sisygambis, the mother of Darius III.