Castor and Pollux, known as the Dioscuri in Greek and Roman mythology, were twin brothers celebrated for their heroic exploits and close bond. They were revered as protectors of sailors and warriors, and their story is intertwined with the constellation Gemini.

Castor and Pollux were the sons of Leda, queen of Sparta, but had different fathers: Castor was the mortal son of King Tyndareus, while Pollux was the immortal son of Zeus, who seduced Leda disguised as a swan.
The twins had different fathers due to a divine encounter between Leda and Zeus. Castor and Pollux were born from two eggs – Castor from an egg laid by Leda and Pollux from an egg laid by Leda while she was visited by Zeus in the form of a swan. This dual paternity was a significant part of their mythological significance.

Castor was killed in battle, and Pollux, unwilling to be separated from his brother, asked Zeus to share his immortality, leading to their transformation into the constellation Gemini.