Who were the Dioskouroi? This study sets out to revisit the evidence and explore the Greeks’ experience of the Spartan brothers Kastor and Polydeukes in image, myth and cult.Commonly equated with the Roman Dioscuri, Castor and Pollux, first by Roman writers in antiquity and subsequently by their western successors, the Greek Dioskouroi are here examined as they were represented in the period before the Roman hegemony of Greece.The evidence is explored through a series of case studies, chosen to focus chiefly on the brothers’ homelands in myth – Sparta, Messene and Argos in the Peloponnese.Also reviewed is their presence on Eastern Aegean shores, and on trading routes where Greeks and other mariners may have sought the protection of the Dioskouroi, above all Thera, Kyrene and Naukratis.Our journey of rediscovery also includes Delos, crossroads of cultures in antiquity.In the process, some fresh perspectives have emerged, not least that Kastor and Polydeukes may not always have been synonymous with the Dioskouroi and, when they were, that appellation may have carried a specific and votive meaning.