Dioscuri (Castor & Polydeuces)

Twins, Castor (Κάστωρ) and Polydeuces (Πολυδεύκης; his name is Pollux in Latin) were the most famous Spartan heroes. Some recorded them both as sons of Tyndareüs (Tyndareus) and Leda, daughter of Thestius, while others said that they were sons of Zeus. Thus they were called Dioscuri (Διόσκουροι). But most writers say that Castor with his sister Clytemnestra were Tyndareüs' children, while Polydeuces and Helen were Zeus', by Leda. Zeus visited and seduced Leda in the form of a swan. So Castor was mortal while his twin was immortal. The mother of Helen was quite often said to be Nemesis, the goddess of retribution, whom Zeus had seduced in the form of a swan. According to the Homeric Hymn, to the Dioscuri, Leda bore the twins on the peak of Mount Taygetus but it doesn't state that their sister Helen was born there too.

Castor became renowned as a horseman and was given a title of Tamer of Horses. Polydeuces was renowned for his skills in boxing. The Dioscuri were identified riding a pair of white horses.

Castor trained the youth Heracles in fencing. They sailed with the Argonauts where Polydeuces killed Amycus, king of the Bebrycians, when he challenged the crew to a boxing match. They also joined with several members of the Argonauts in the Calydonian boar hunt. The Dioscuri and Jason also helped Peleus in capturing Iolcus from Acastus.

When Theseus and Peirithoüs (Peirithous) abducted their sister Helen, the Dioscuri captured Athens and returned Helen to Sparta, with Theseus' mother held as captive. Theseus also lost the throne to another Athenian named Menestheus whom the Dioscuri installed as king of Athens. (Menestheus was later a suitor of Helen. He led fifty ships to Troy.)

Their main rivals and enemies were their cousins: Idas and Lynceus, sons of Aphareus. When Idas and Lynceus were going to marry their cousins, Phoebe and Hilaera, daughters of Leucippus, the Dioscuri abducted them and married the girls themselves. Hilaera bore Anogon to Castor, while Phoebe bore Mnesilus to Polydeuces.

When they raided some cattle with Idas and Lynceus, they decided on a contest of who would get all of the cattle. Idas and Lynceus won the contest and drove their prize back to Messene. Castor and Polydeuces decided to take the cattle back in a raid. Lynceus warned Idas of their approach and ambushed the Spartan twins. In the fighting that followed Polydeuces killed Lynceus, but was felled by a rock hurled by Idas. Zeus, protecting his son, killed Idas with a thunderbolt.

Polydeuces was grief-stricken by the death of Castor at Idas' hand. The immortal Polydeuces wanted to die with his brother. Taking pity on his mourning son, Zeus decided that the twins would share their immortality: they would spend their days living alternately both (or separately) in Olympus and the Underworld.

Zeus placed them as the constellation Gemini in the heaven. They became gods in Sparta where they were patrons of warlike youths and sailors in the stormy sea.

According to Homer in the Iliad, Helen wondered where her brothers were because she did not see them among the Greeks fighting in the war, not realising that they had already died. This suggested that her brothers, Castor and Polydeuces, had died after she ran off with Paris to Troy.