Claim: Gregor Clegane is a character from the HBO series Game of Thrones.
Evidence: 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.
The series premiered on HBO in the United States on April 17 , 2011 , and its sixth season ended on June 26 , 2016.