Robb Stark

Eddard Stark's eldest son, proclaimed King in the North by his father's bannermen after Joffrey took Ned's head. He was barely more than a boy and won battle after battle regardless, which would have delighted Robert enormously and told him nothing useful about what came next.

Robb is one of the five kings of the war that followed Robert's death — the direct consequence of a realm held together for fifteen years by one man's reputation and nobody's actual governance. When the reputation died on a boar's tusks, the rest went with it.