The dominant religion of the Seven Kingdoms south of the Neck, brought to Westeros by the Andals and holding that one god shows seven faces — Father, Mother, Warrior, Smith, Maiden, Crone and Stranger. Its quarrel with House Targaryen was doctrinal before it was ever military: the Faith condemned the Targaryen practice of marrying sibling to sibling, and of taking more than one wife.

That quarrel armed itself in the militant orders — the Warrior’s Sons and the Poor Fellows — and became The Faith Militant Uprising under Aenys I and Maegor the Cruel. Jaehaerys I ended it by negotiation rather than dragonfire, trading the disarmament of the orders for the Crown’s guarantee of the Faith’s freedom of worship.