Thersanon

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, who was himself a son of Helios and thus one of Thersanon's paternal half-brothers.

Parentage
Hyginus names Leucothoe as his mother; according to Ovid, Leucothoe was a mortal princess of Babylon that Helios fell in love with; but when her father discovered the affair thanks to Clytie, he buried Leucothoe alive, and afterwards her dead body was turned into a frankincense tree by Helios. Hyginus assigning them a son might indicate that he knew a very different version of the myth in which Leucothoe survives, or at least lives long enough to bear a child; alternatively Hyginus is perhaps referring to another woman, such as the sea goddess Leucothea, whom he elsewhere refers to as "Leucothoe" in the same work.