HBO Game of thrones season 7 GoT cast Mountain hafthor bjornsson Gregor Clegane

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No other knight in the service of the House Lannister strikes as much fear into the hearts of opponents as Gregor Clegane. Hafþór Júlíus Björnsson plays the fearsome warrior who is nicknamed The Mountain due his towering physique and sheer brute strength. Fans still remember the shocking moment the mountain used his bare hands to crush the skull of Oberyn Martell (Pedro Pascal) at the end of season four. Moments before he brutally killed Oberyn, The Mountain was struck with spear dipped in deadly manticore poison which seemingly killed him.

But this was not the end of his story and his rotting copse was reanimated by the dark and twisted sciences of maester Qyburn (Anton Lesser) to serve as Cercei’s (Lena Headey's) bodyguard. Outside of Game of Thrones, Hafþór’s muscular physique is just as impressive and is testament to his exercise regime. Standing 2m tall and weighing nearly 200 kg, Hafþór was the perfect casting choice to portray the brutal head of House Clegane. In HBO’s casting department suggested that the action should audition for the part in the fantasy epic in 2014.

GETTY The Icelandic strongman joined the cast of Game of Thrones in 2014

HBO The Mountain died from poisoning after killing Oberyn Martell in a duel

I thought it was some kind of joke. I had no acting experience. I was just a big dude competing in Strongman Hafþór Júlíus Björnsson, Game of Thrones actor

“I thought it was some kind of joke. I had no acting experience,” he told Men’s Health. “I was just a big dude competing in Strongman.” The Mountain had been played by two different actors over the first three seasons, but the series needed a more permanent face. Having played professional basketball for a few years, he was more agile and faster than the other candidates. This proved a bonus given all the sword work involved in the role. “A lot of big guys can’t bend down, have knee pain, are slow,” Björnsson said. “I’m fast. I’m flexible, especially for my size.”

The cast of Game of Thrones in real life Tue, July 18, 2017 Game of Thrones: See what the amazing cast look like in real life. Play slideshow Getty•HBO 1 of 15 Lena Headey as Cersei Lannister

But the Icelandic strongman was not always this big and in fact he was quite lanky during his basketball days. “I was always taller than everybody else,” he told GQ in 2016. “I’ve been training all my life, but probably didn’t grow muscle-y until I quit doing basketball. “I played for Iceland’s under-18 and under-17 team, so it wasn’t until probably 2007, 2008 that I start to gain a lot of weight.” Hafþór took up weightlifting after a series of ankle injuries forced him to bow out of basketball. He soon fell in love with the weights and embarked on a routine of eating and exercising that allowed him to impressively bulk up.

HBO Hafþór Björnsson was a basketball player before he took up professional weightlifting

HBO The Mountain's corpse was reanimated as Cercei's personal bodyguard