Euron Greyjoy is the younger brother of Lord Balon Greyjoy and captain of the Silence, a ship crewed entirely by mutes whose tongues Euron ripped out. Euron is a wildly unpredictable man, known for his delight in playing vicious mind games and waging psychological warfare on those around him. He is a pale and handsome man with raven black hair, a neat dark beard, blue lips and bright blue eyes. He wears a patch over his left eye, and is nicknamed "Crow's Eye", though it is unclear what he hides beneath the patch. He was banished from the isles by Balon for seducing Victarion's wife and warned never to return while Balon was alive.

Euron returned to the isles the day after Balon's death, the timing of which strongly implied his involvement. He had not been seen in the Iron Islands for over two years and claimed to have reaved all over the world during his exile, including a trip to the feared ruins of Valyria. He also captured and holds hostage several warlocks of Qarth, who may have coached him in black magic.

At the Kingsmoot called by Aeron Greyjoy, he promised to conquer all Westeros for the Ironborn using dragons, which he claimed he could bind to his will with a magic horn. He was chosen as the new king and began raids upon the Reach. These raids were wildly successful, and Euron weakened possible rivals by giving lands and titles to key followers of theirs. However, he failed to move the Ironborn beyond raiding and to continue their quest for the dragons. Instead, he sent Victarion to find Daenerys Targaryen, court her in his name, and bring her and her dragons to Westeros.

Previously, at the start of Greyjoy's rebellion, Euron executed his own plan to sail into Lannisport and burn the Lannister fleet at anchor. This earned him a reputation for cunning he has never lost.