A younger prince of Dorne, Oberyn Martell was also a fierce fighter who earned the nickname the "Red Viper." He spent time in the Citadel but quit his studies before earning a full set of links. Prince Oberyn acted as Tyrion Lannister's champion during Tyrion's trial by combat for the murder of King Joffrey. He hoped to gain revenge against the crown's champion, Gregor Clegane, whom he believed had murdered his sister. He struck a mortal but then was himself killed as he got too close to the man known as the Mountain.