House Baratheon of King's Landing is an extinct cadet branch of the also extinct original House Baratheon of Storm's End. It had been the royal house of Westeros since the defeat of and exile of the Targaryen dynasty following Robert's Rebellion.
Their seat was the Red Keep in the city of King's Landing and their domains were the lands ruled directly by the Iron Throne, the Crownlands. After the Destruction of the Great Sept of Baelor, with King Tommen I's suicide, House Baratheon of King's Landing is now extinct, along with its parent house, House Baratheon.