House Greyjoy of Pyke is one of the Great Houses of Westeros and the principal noble house of the Iron Islands. They claim descent from the Grey King of the Age of Heroes, who ruled the western seas, took a mermaid to wife, and made his hall from the bones of Nagga, a leviathan he slew.
After Harren the Black burned with his sons in Harrenhal, Aegon the Conqueror summoned the captains and kings of the ironborn and bade them choose a new lord paramount. They chose Vickon Greyjoy of Pyke, and the kraken has flown above the salt-wet keep ever since. Lord Balon Greyjoy rose against the Iron Throne nine years before the events of A Game of Thrones. The rebellion ended on the bridge between his towers, with his elder sons dead and his last son, Theon, given over to Eddard Stark as ward and hostage.