House Stark of Winterfell is one of the Great Houses of Westeros and the principal noble house of The North; many lesser houses are sworn to them. In days of old, they ruled as Kings of Winter. Since the Targaryen Conquest, they have been Wardens of the North. Their seat, Winterfell, is an ancient castle renowned for its strength.
Their sigil is a grey direwolf racing across a field of white, and their words are "Winter Is Coming' - one of only a few house mottos that sounds to be a warning rather than a boast. Members of House Stark tend to be lean of build and long of face, with dark brown hair and grey eyes. Several of the main point of view characters of the series are members of this house.
House Targaryen is a noble family of Valyrian descent that escaped the Doom. They lived for centuries on the island of Dragonstone until Aegon Targaryen and his sisters rode their dragons to the conquest of the Seven Kingdoms. House Targaryen ruled as the Kings of Westeros for nearly 300 years, until ousted in the War of the Usurper. Their seats were the capitol city of King's Landing and the island castle of Dragonstone. Members of this house have silvery blonde hair and light or violet eyes, and their house words are 'Fire and blood.'Get all the Targaryen gear you can handle for 20% off!
House Tyrell of Highgarden is one of the Great Houses of the Seven Kingdoms, overlords over the Reach. A large, wealthy house, its wealth is only surpassed among the Great Houses by House Lannister, and the Tyrells can field the greatest armies. Additionally, if they call the fleets of their bannermen, the Redwynes, the lords of the Shield Islands, and the coastal lords, they can command a navy that equals, perhaps surpasses the royal fleet.
Highgarden is an ancient seat of rule and the heart of chivalry in the Seven Kingdoms. The Tyrells style themselves 'Defenders of the Marches' and 'High Marshals of the Reach,' and traditionally, they have been Wardens of the South. Their sigil is a golden rose on a green field, and their words are "Growing Strong." Members of the family tend to have curly brown hair and brown or golden eyes.
House Nymeros Martell of Sunspear is one of the Great Houses of Westeros and the ruling house of Dorne. 'Nymeros' indicates "of the line of Nymeria," but generally it is simply called House Martell. The Martells of old used a spear as their emblem, while Nymeria and the Rhoynar used the sun as theirs.
These were combined when Nymeria wed King Mors Martell, making a sigil of a gold spear piercing a red sun on an orange field. Their words are, 'Unbowed, Unbent, Unbroken.' In appearance, they are classic salty Dornishmen, with dark eyes, dark hair in ringlets, and olive skin.