In Hindu mythology, Rahu was an asura who disguised himself as a deva to drink amrit during Samudra Manthan. Vishnu detected him and beheaded him with his Sudarshana Chakra, but since the amrit had already reached his throat, Rahu became immortal. Ketu is actually Rahu's detached body, while Bali was a different asura king known for his generosity.