Ser Rodrik Cassel was a member and knight of House Cassel, and the master-at-arms at Winterfell, as well as a loyal servant of House Stark. Following the attempted assassination of Bran Stark, Ser Rodrik accompanied Catelyn Stark to King's Landing to warn her husband, before returning to Winterfell, where on their way they found and captured Tyrion Lannister, taking him to the Eyrie to face justice. Tyrion managed to get himself free through trial by combat, and shortly after the Vale refused to join forces with the North, Ser Rodrik and Catelyn returned North to join Robb's host. Upon reaching it, Catelyn names him castellan of Winterfell, and he returns shortly after. During an ironborn invasion, Ser Rodrik takes a large force, including the Winterfell garrison, to repulse them at Torrhen's Square, unknowingly allowing Winterfell to be taken. In the books, Ser Rodrik gathers more men and a larger force and lays siege to Winterfell, only to be suddenly attacked by Bolton forces led by Ramsay, who then executes Ser Rodrik, before sacking Winterfell. In the show, the ironborn defeat Ser Rodrik's initial force and capture him, dragging him to Winterfell, where he is executed (albeit, clumsily) by Theon Greyjoy to set an example for his troops.