Storm God

The Storm God is a malevolent deity in the religion of the Drowned God, followed in the Iron Islands of Westeros.

The Drowned God is a harsh, war-like deity who drowned so that the ironborn might live, then rose again from the wave, harder and stronger. The Drowned God brought fire from the sea for the ironborn, and made them to be fierce warriors and sailors. The Drowned God is the only deity that the ironborn worship.

Within the ironborn religion, the Drowned God is locked in an age-old struggle against his enemy the Storm God. The Drowned God's halls are located beneath the ocean, while the Storm God lives in a castle in the sky with his thunderclouds. The Storm God is constantly trying to send storms to dash ironborn ships against rocks to their ruin.

In the books
In the A Song of Ice and Fire novels, the Storm God is the devil-figure in the ironborn religion, fighting against their true deity, the Drowned God. The mythos of the ironborn religion is loosely inspired by real-life Viking mythology