House Baratheon of Dragonstone is a cadet branch of the original House Baratheon of Storm's End. It rules over the island of Dragonstone after the defeat of House Targaryen in Robert's Rebellion. Stannis Baratheon, the head of the house and the Lord of Dragonstone, was a claimant to the Iron Throne in the War of the Five Kings.
Their seat is the island fortress of Dragonstone in Blackwater Bay. The houses of Blackwater Bay, also known as the Lords of the Narrow Sea, are sworn directly to Dragonstone.
Their house words were "Ours Is the Fury," which they shared with their overlords and fellow cadet branches. However, the most common saying of the house was "For The Night is Dark and Full of Terrors." This was also a common saying of followers of R'hllor, the Lord of Light, who was the official religion of the house due to the influence of the red priestess Melisandre.