Castor and PolluxCas‧tor and Pol‧lux /ˌkɑːstər ənd ˈpɒləks $ ˌkæstər ənd ˈpɑː-/in ancient Greek and Roman stories, two brothers who were twins (=two children born at the same time), and who had many adventures. The group of stars known as gemini or the Heavenly Twins is named after them.