House Stark of Winterfell is one of oldest of the Great Houses of Westeros. They trace their line back to the First Men, and once ruled as Kings of the North.
Their sigil is a grey direwolf on a field of white, and their words are "Winter is Coming".
House Lannister of Casterly Rock is a rich and powerful dynasty.
Their sigil is a golden lion on a crimson field, and their words are "Hear me roar!", but their unofficial motto, is "A Lannister always pays his debts."
House Targaryen is a noble house of Valyrian descent.
Their sigil is a three headed red dragon on a field of black. The three heads represent Aegon the Conqueror and his sisters, Rhaenys and Visenya. Their words are "Fire and Blood"
House Baratheon of Storms End is one of Great Houses of Westeros, and principal house of the Stormlands. The Baratheons and their bannermen were instrumental in the rebellion against Targaryens.
Their sigil is a crowned black stag on a field of gold, and their words are "Ours is the Fury".
House Greyjoy of Pyke rules over the Iron Islands.
Their sigil is a kraken (giant squid) on a black field, and their words are "We Do Not Sow", a reference to their intention to take what they want by raiding - to "pay the iron price".
House Tully of Riverrun, is a Great House of Seven Kingdoms, that rules over the Riverlands from their seat at Riverrun.
The Tully's are aligned with Winterfell through the marriage of Catelyn to Eddard Stark.
Their sigil is a silver trout leaping on a blue and red striped field, and their words are "Family, Duty, Honor."
House Arryn of the Eyrie is one of Great Houses of Westeros, and is the principal noble house in the Vale.
Their sigil is a white moon-and-falcon on a sky-blue field, and their words are "As High as Honor."
House Tyrell is one of the Great Houses of Westeros. It rules over the Reach, a vast, fertile, populous region of south-western Westeros.
Their sigil is a golden rose on a green field. Their words are "Growing Strong".
House Martell is one of the Great Houses of Westeros, ruling over the peninsula of Dorne in the far south.
Their sigil is a sun pierced by a golden spear. Their words are "Unbowed, Unbent, Unbroken."
House Frey is a vassal of House Tully of the Riverlands and holds its fealty to the Lord of Riverrun.
Their castle is known as the Twins, for its two identical keeps on either side of a river linked by a bridge, sometimes called the Stone Bridge.
Their sigil is two grey towers linked by a bridge.