Cástor

Cástor is the Spanish and Portuguese form of the Greek name Castor. In Greek mythology, Castor was one of the Dioscuri, twin sons of Leda and either Zeus or Tyndareus. He was a skilled horseman and along with his brother Pollux, was revered as a patron of sailors and athletes. The name's etymology is believed to be derived from the Greek word 'kastor' (κάστωρ), meaning 'beaver'.

The twins Castor and Pollux were central figures in ancient Greek and Roman religion and myth. Their story, particularly their inseparable bond and eventual deification, made the name significant. The constellation Gemini is associated with them. The name has seen continued use in various forms, particularly in Romance language-speaking countries, often due to its mythological and historical connections.