According to Greek and Roman mythology, these were twin sons of Zeus. The apostle Paul sailed from Malta to Puteoli on a ship whose sign or figurehead was the "Twin Brothers" (Acts 28:11). These twin brothers were also known as the Dioscuri (which means "sons of Zeus").
Castor and Pollux
From Tyndale Bible Dictionary, adapted by Mission Mutual. CC BY-SA 4.0.