Gregor Clegane was introduced in the television series Game of Thrones.
The first season of the fantasy drama television series Game of Thrones premiered on HBO on April 17 , 2011 , at 9.00 pm in the U.S. , and concluded on June 19 , 2011 . The third season of the fantasy drama television series Game of Thrones premiered in the United States on HBO on March 31 , 2013 , and concluded on June 9 , 2013 . 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 . Introduced in 1996 's A Game of Thrones , Gregor is the older brother of Sandor Clegane , from the fictional kingdom of Westeros .