The Mountain Is Cersei's New Guard On 'Game Of Thrones' & He's The Backup She Needs To Get Back On Top. Gregor Clegane broke Game Of Thrones fans' collective hearts last season when he crushed Oberyn Martell's skull like an egg during Tyrion's Trial By Combat. The enormous brother of The Hound (R.I.P?) was mortally wounded during the fight but Qyburn, a disgraced former maester, reanimated him to become The Mountain, Cersei's new bodyguard.