House Lannister led by King Loren I Lannister

House Lannister of Casterly Rock is one of the Great Houses of Westeros, one of its richest and most powerful families and oldest dynasties. Though not officially the royal house, the Lannisters do in truth control the Iron Throne. The major characters Jaime, Cersei, and Tyrion and the recurring characters Tywin, Kevan, and Lancel are members of the house. Tywin is the head of House Lannister and Lord of Casterly Rock.
Their lands are in the far west of the continent. Their seat is Casterly Rock, a massive rocky promontory overlooking the Sunset Sea which has had habitations and fortifications built into it over the millennia. They are the Lords Paramount of the Westerlands and Wardens of the West. House Lannister's Heraldry consists of a golden lion on a crimson background, and their House words are "Hear me roar!", which is rarely mentioned. Their unofficial motto, which is as well known as the official one, is "A Lannister always pays his debts" - which is used much more often and mostly in negative context, though it can also be used in the original, literal sense.