Great houses are the most powerful noble houses of the Seven Kingdoms, often being former royalty and now sworn directly to the Iron Throne. The book, The Lineages and Histories of the Great Houses of the Seven Kingdoms, by Maester Malleon, describes the lineages of the great houses and high lords of Westeros in explicit detail.
House Stark of Winterfell Edit
House Targaryen conquered most of Westeros during Aegon's Conquest. House Stark of Winterfell, the former Kings in the North, became Wardens of the North for the new king, Aegon I Targaryen.
The current House Stark of Winterfell are the descendants of Lord Jon Stark, legitimized by the Targaryens, and his wife Lady Wylla Manderly.
House Arryn of the Eyrie Edit
House Arryn of the Eyrie, the former Kings of Mountain and Vale, became the Wardens of the East.
The current House Arryn of the Eyrie are the descendants of Lord Harrold Arryn and Lady Sansa Stark.
House Lannister of Casterly Rock Edit
House Lannister of Casterly Rock, the Kings of the Rock, became the Wardens of the West, the wealthiest of the Great Houses.
The current House Lannister of Casterly Rock are the descendants of Lord Tyrek Lannister and Lady Margaery Tyrell.
House Tyrell of Highgarden Edit
House Gardener of Highgarden, the Kings of the Reach, were extinguished at the Field of Fire by Aegon's dragons. Aegon granted Highgarden to House Tyrell, his new Wardens of the South. Despite being sworn to the Tyrells, the Hightowers of Oldtown are among the oldest and proudest of the Great Houses of Westeros.
The current House Tyrell of Highgarden are the descendants of Lord Willas Tyrell and Lady Talla Tarly.
House Tully of Riverrun Edit
House Hoare of Harrenhal, the Kings of the Isles and the Rivers, were extinguished in the burning of Harrenhal. Aegon granted dominion over the Riverlands to House Tully of Riverrun, the new Lords Paramount of the Trident.
The current House Tully of Riverrun are the descendants of Lord Edmure Tully and Lady Roslin Frey.
House Greyjoy of Pyke Edit
Aegon allowed the Iron Islands to choose House Greyjoy of Pyke as their new liege lords.
The current House Greyjoy of Pyke are the descendants of Lady Asha Greyjoy and Lord Gran Goodbrother.
House Baratheon of Storm's End Edit
Aegon's half-brother, Orys Baratheon, slew Argilac the Arrogant, the last Storm King from House Durrandon. Orys married Argilac's daughter, Argella Durrandon, forming House Baratheon of Storm's End, the youngest of the Great Houses of Westeros.
The current House Baratheon of Storm’s End are the descendants of Lord Edric Baratheon, legitimized by the Targaryens, and Lady Shireen Baratheon.
House Martell of Sunspear Edit
The principality of Dorne, ruled by House Martell of Sunspear, resisted Aegon in the First Dornish War. The Martells later peacefully joined the Seven Kingdoms during the reign of King Daeron II Targaryen.
The current House Martell of Sunspear are the descendants of Prince Trystane Martell and Princess Myrcella Baratheon.
House Targaryen of King's Landing Edit
Aegon created the crownlands around Blackwater Bay, with House Targaryen ruling from the Iron Throne. The Targaryens were eventually deposed during Robert's Rebellion, however, and the crownlands were then ruled by House Baratheon of King's Landing until 301 AC.
The current Houses Targaryen of King's Landing, Dragonstone, and Summerhall, are the descendants of Aegon VI Targaryen and Daenerys I Targaryen.