From A Wiki of Ice and Fire
Grey King fighting Nagga
|Reign||During the Age of Heroes|
|Other Titles||High King of the Iron Islands|
|Books|| A Game of Thrones (mentioned)|
A Dance with Dragons (mentioned)
The World of Ice and Fire (mentioned)
The Grey King is a legendary hero from the Iron Islands.
The legends say the Drowned God himself helped the Grey King to slay the sea dragon Nagga. From her bones he made his hall, the Grey King's Hall, which he heated with Nagga's living fire. For a thousand years he reigned. He took a mermaid as his wife so his sons and daughters might live above or beneath the waves as they chose. His hair and beard and eyes were as grey as the winter sea, and from them he took his name. He also wore a crown of driftwood so all who knelt before him would know his power came from the sea and the Drowned God himself.
The Grey King brought fire to the earth by taunting the Storm God until he lashed down with a thunderbolt and set a tree ablaze. He also taught men to weave nets and sails and carved the first longship from the pale wood of Ygg, a demon tree who fed on human flesh.
He supposedly wore robes of woven seaweed and a tall pale crown made from Nagga's teeth. When the Grey King died, the Storm God snuffed out the fire and the sea stole his throne. Only his hall remains. Another account states that he ruled for a thousand years until his skin turned as grey as his hair and bear. Then he cast aside his driftwood crown and walked into the sea to descend to the watery halls of the Drowned God to take his place at the right hand of the god.
The Grey King is said to have had a hundred sons who fought after his death. The sixteen who survived divided the Iron Islands amongst themselves. All of the great houses of the islands claim descent from the Grey King, including House Greyjoy, with the exception of House Goodbrother, who claim descent from the Grey King's loyal eldest brother.