Dioscuri (dye-us-KOO-ree). The Hero Twins of Sparta, Castor and Polydeuces. When Theseus abducted their sister, later renowned as Helen of Troy, they succeeded in rescuing her. Since Polydeuces was immortal and Castor was not, they were at first separated after death. Polydeuces was admitted to Olympus while Castor was sent to the Underworld. But the gods relented and allowed them to spend eternity together, half the year in one place and half in the other.