"You raped her! You murdered her! You killed her children!" Sorry, wrong script. Watch UFC featherweight contender (145 pounds) Conor McGregor sparring with the 6'9", 400 pound actor who portrayed The Mountain, Gregor Clegane, on HBO's Game of Thrones. The actor in the famous TV show is Hafthór Júlíus Björnsson, a 26-year-old strongman competitor from Iceland. If all the chips were actually on the line here, who would you pick? Oberyn Martell (Conor McGregor) or The Mountain? I gotta say, it would be a tossup. McGregor will be back in MMA action in December when he challenges Jose Aldo for the featherweight crown.