Lewyn Martell was the uncle of Prince Doran Martell, Elia and Oberyn Martell. He was a member of the Kingsguard and legendary for his skill with the spear. He also had a paramour, but his sworn brothers never revealed his secret.

King Aerys II used Lewyn's niece Elia, Rhaegar Targaryen's wife, as a hostage to force Lewyn to lead an army of Dornishmen to fight against Robert Baratheon. He fought at the Battle of the Trident alongside Prince Rhaegar and was wounded a dozen times. He was finally killed by Ser Lyn Corbray and his Valyrian steel sword, Lady Forlorn.