Dalton Greyjoy

Lord Dalton Greyjoy is an unseen character in Game of Thrones. He was the Lord of the Iron Islands during the Dance of the Dragons.

Biography
After Aegon I Targaryen conquered Westeros, the Ironborn were forced to end their reaving and abandon the Old Way. The Ironborn would tell each other tales of how they would eventually rise again, something that caught the attention of Dalton, who was the wild young heir to Pyke. He rowed at the age of five, reaved at ten in the Basilisk Isles with his uncle, and by the age of fourteen, he had sailed as far as Old Ghis, fought in a dozen battles and claimed four salt wives. At the age of fifteen, he avenged his uncle's death in battle, taking a dozen wounds, and his entire ended up covered in blood, earning the nickname "the Red Kraken".

During the Dance of Dragons, Dalton and the Ironborn sided with Rhaenyra Targaryen's Blacks since it allowed them to attack the Westerlands held by House Lannister, whose troops away fighting for Aegon II Targaryen's Greens. The Ironborn were not able to take Casterly Rock, since Lady Johanna Lannister was able bar its gates, and they instead burned the Lannister fleet and sacked Lannisport, taking gold, grain and hundreds of women and girls, including Lord Jason Lannister's favorite mistress and all his bastards.

Dalton controlled the Sunset Sea and had returned the Ironborn to the Old Way. After the end of the war, the Iron Throne commanded that he stop his plundering, but Dalton refused. Shortly afterwards, his mistress Tess slit his throat while he was asleep, causing succession dispute between his sons. The Lannisters used the opportunity to send troops to the Iron Islands, who killed thousands of men, women and children, and burned scores of villages and hundred of longships.

Reference

 * "The Old Way"