The greatsword of Ser Gregor Clegane, the Mountain That Rides, was an oversized blade of plain steel so heavy and so long that few other men could have raised it in two hands. Gregor, a giant of a man near eight feet tall, swung it one-handed as easily as another knight might wield an arming sword, and with it he cut men and horses near in half.
He carried it through the War of the Five Kings until his duel with Prince Oberyn Martell, whose poisoned spear left the Mountain dying by inches. The blade outlasted its master's monstrous strength.
Status: extant.