Rhadamanthus was a king in Greek mythology, son of Zeus and Europa and brother of Sarpedon and Minos. Rhadamanthus as well as his brother Minos later became two of the three judges of the dead in the Underworld. According to some sources, Rhadamanthus married Ariadne, the daughter of Minos and therefore, his niece; she should not be confused with another Ariadne, who was the daughter of Minos' grandson and who had a role in the adventures of Theseus. At some point, Rhadamanthus was exiled from Crete by Minos and went to Boeotia, where he married Alcmene.
Rhadamanthus is also called Rhadamanthys.