By now, most Game of Thrones fans know that Hafþór Júlíus Björnsson plays the part of The Mountain, Gregor Clegane, but considering how often he wears a mask, we thought we should include him on this list. Besides, the character has switched between three actors since the beginning of the show, so it can be difficult to keep up. In season one, Gregor was played by Conan Stevens. After season one, Stevens left after being cast as Bolg in The Hobbit trilogy (a role that was almost completely edited out too). Ian Whyte, an actor who has played white walkers and giants on Game of Thrones, took over as Gregor for season two. In season four, Gregor’s role became much more central when Cersei took him as her champion. It was here that Björnsson took on the role. For those who are unaware, Björnsson is a four-time World’s Strongest Man winner. Standing 6 feet 9 and weighing 400 lbs, this is a terrifying human.