Vickon Greyjoy

Vickon Greyjoy is an unseen character in Game of Thrones He is not expected to appear, being long dead by the time it begins.

Lord Vickon was the head of House Greyjoy and the Lord Reaper of Pyke during the reign of King Harren the Black of House Hoare. After Harren and his line were burned alive by Aegon the Conqueror inside his castle of Harrenhal, the ironborn were expelled from the Riverlands back to the Iron Islands. In exchange for their allegiance, Aegon allowed to ironborn to choose their new leader. They chose Vickon Greyjoy.

In the books
In the A Song of Ice and Fire novels, Vickon Greyjoy's story is the same