Jason

Jason was captain of the Argo., and was one of many heroes taught by Chiron. Born as the son of Aeson, the king of Iolcos. His given name was Diomedes, but when he was taken by Chiron, his name was changed to Jason.

When Jason arrived in Colchis. Jason was supported by the Goddess Aphrodite, and upon realizing that the King of Colchis was unshakable, she decided to control the mind of his daughter Medea to help Jason. Medea was made to blindly love Jason, which resulted in her betraying her father and her country for a foreigner she had never seen. Her abilities allowed her to nullify her father's magic and the enchanted fire-breathing oxen, which gave Jason the chance to obtain the Golden Fleece.

In Fate/Grand Order, Jason has the appearance of a young man with blond hair. In the anime adaption of Fate/Stay Night, however, Jason has dark hair.