Theras (Ancient Greek Θήρας) was a Theban Cadmid, son of Autesion and brother of Argeia, who served as regent of Sparta for his nephews Eurysthenes and Procles. Herodotus and Pausanias credit him with leading Minyan and Spartan settlers to the island thereafter called Thera (Santorini) in his honour.
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I.Spartan regency
Through his sister Argeia, wife of Aristodemus, Theras was maternal uncle of the twin Heraclid kings Eurysthenes and Procles. While they were under age he governed Sparta as regent — a Cadmeid bridging Theban and Lacedaemonian stems.
Herodotus (Histories 4.147–148) and Pausanias (3.1.6–7 and related Laconia notes) preserve the outline: Cadmeid blood at Sparta, then a colonial venture once the twins could rule alone.
II.Founding of Thera
Theras led fellow Spartans and Minyan settlers to the Aegean island previously called Calliste. The new community took his name as Thera. The legend supplies the eponym for the Dorian island that later sent colonists to Cyrene.
The atlas id theras is this regent-founder, son of Autesion (autesion-theban). He is not a Homeric warrior or a later historical Theraean.