Castor and Pollux

Castor and Pollux are twin half brothers in Greek and Roman mythology known together as the Dioscuri. Their mother was Leda, but they had different fathers: Castor was the mortal son of Tyndareus, king of Sparta, while Pollux was the divine son of Zeus, who had come to Leda in the form of a swan, making the twins an example of heteropaternal superfecundation and half brothers of Helen of Troy and Clytemnestra. When Castor died, Pollux asked Zeus to share his own immortality with his brother, and the two were transformed together into the constellation Gemini. The Dioscuri were venerated as patrons of sailors, who saw them in the electrical phenomenon named for Saint Elmo, and as patrons of horsemanship, reflecting their origin in the wider Indo European myth of divine horse twins. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/