In Greek mythology, Thersanon or Thersanor is one of the Argonauts, the crew of the legendary Argo. Born on the island of Andros, Thersanon was the son of the sun god Helios by a woman named Leucothoe; he joined Jason and the other Argonauts in the quest for the golden fleece, kept by King Aeëtes of Colchis, one of Thersanon's paternal half-brothers.