Gregor Clegane is a fictional dog.
Conan Stevens . He is best known for his role as Gregor Clegane in the first season of HBO series Game of Thrones . Ser Gregor Clegane , nicknamed The Mountain , is a fictional character in the A Song of Ice and Fire series of fantasy novels by American author George R. R. Martin , and its television adaptation Game of Thrones . Ser Gregor Clegane is a huge knight and the elder brother of Sandor Clegane . When they were children , Gregor shoved Sandor 's face into a brazier , gruesomely scarring him . A knight is a person granted an honorary title of knighthood by a monarch or other political leader for service to the monarch or country , especially in a military capacity .