Hafthor Bjornsson, known to many as ‘The Mountain’ thanks to his character in the HBO hit show Game of Thrones, has had quite an incredible journey from basketball player to powerlifter.

With that journey comes quite a remarkable body transformation, and a video on YouTube has documented just that with the Icelandic growing in size from the age of 16 to the age of 30.

Standing at six feet and nine inches tall, the strongman was formerly a basketball player in his native Iceland, starting at Breiðablik before enjoying spells at FSu and KR.

After helping FSu reach promotion to the sport’s top flight in Iceland, a recurring ankle injury saw him swap the courts for the gyms; where he would win the Iceland's Strongest Man in 2011, before becoming Europe's Strongest Man in 2014, 2015, 2017, 2018, and 2019.

Bjornsson was crowned World Champion in 2018, before breaking Eddie Hall’s deadlift record just last month as he lifted 501 kilograms live on ESPN.

The video shows a remarkable transformation, starting off as an averagely built 16-year-old before being pictured lifting a boulder just three years later.

By the age of 21, Bjornsson saw his first strongman glory, before the video shows him dragging a lorry down a road just a year later.

You can watch the remarkable body transformation journey in the video below.

The 31-year-old’s role in Game of Thrones is pictured rather menacingly in the video, where he played Gregor ‘The Mountain’ Clegane for five seasons before his character’s untimely demise in the penultimate episode of season eight.

As you can see, it's been one hell of a journey for Bjornsson, and his body is only going to change more so as he prepares to swap Strongman competition for the boxing ring.

He will share the ring with Hall next year in Las Vegas as the two look to settle their feud once and for all.