Hafþór Júlíus Björnsson is an Icelandic professional strongman, actor, and former professional basketball player.
He plays Ser Gregor "The Mountain" Clegane in the HBO series Game of Thrones.
Superman and the rest of the Justice League unite to battle a hulking monster named Doomsday -- but it's ultimately up to the Man of Steel to save the day as the two titans square off in the heart of Metropolis.
