Griffin's Roost is a castle in the Stormlands, the region controlled by House Baratheon of Storm's End. It is the seat of House Connington. The castle is located south-west of Storm's End on the western edge of Shipbreaker Bay.
In the books
In the A Song of Ice and Fire novels, Griffin's Roost is the seat of House Connington.
Prior to Robert's Rebellion, the young Lord Jon Connington was one of Prince Rhaegar Targaryen's closest friends and allies. During the rebellion, the Mad King promoted Connington to the rank of Hand of the King and tasked him with destroying Robert Baratheon's rebel army before it could join with the forces being gathered by Houses Stark, Arryn and Tully in the Riverlands.
Following Robert's defeat at the Battle of Ashford, Connington's forces pursued Robert north to Stoney Sept, trapping him in the town. Connington refused to raze the town, instead conducting a house-to-house search whilst Robert was hidden by rebel sympathizers. Connington was still searching when Eddard Stark arrived with a rescue force. In the resulting Battle of the Bells, Connington was defeated and his army repulsed from the town with heavy losses.
King Aerys was furious with Connington's failure. He was stripped of lands and titles and sent into exile in the Free Cities, where it is rumored that he drank himself to death after a brief stint with the Golden Company. After taking the Iron Throne, King Robert granted Griffin's Roost to Jon's cousin Ronnet, who had joined the rebellion after Jon's exile. However, most of the Connington lands were distributed among more fervent supporters of the rebellion. The lordship wasn't restored either so House Connington was reduced to the status of knightly house.