Hafthor Julius Bjornsson has proved why he is the reigning World's Strongest Man by breaking his own deadlift world record at the 2019 Arnold Strongman Classic.

Key points: Bjornsson performed a world record 474kg Rogue Elephant Bar deadlift

Bjornsson performed a world record 474kg Rogue Elephant Bar deadlift The Game of Thrones star described the lift as a "pretty casual new world record"

The Game of Thrones star described the lift as a "pretty casual new world record" The Icelander won the World's Strongest Man title for the first time last May

In a feat of strength more befitting the fantasy world of swords and sorcery, the Game of Thrones star set the Rogue Elephant Bar deadlift world record with a 474-kilogram lift at the event in Columbus, Ohio, raising his arms in triumph after he dropped the straining bar to the ground.

The man who plays The Mountain went on to claim the Arnold Strongman Classic championship for the second straight year, with first place finishes in two other events — the Husafell Stone Carry and the Austrian Oak.

The performance capped off a stellar 12 months for the 30-year-old, who claimed his first World's Strongest Man title last May.

Despite his record-breaking feats, Bjornsson took winning his latest title in his stride.

Hafthor Julius Bjornsson as The Mountain, Gregor Clegane, in Game of Thrones. ( Supplied )

On Instagram, the Icelander said he was disappointed he was not successful with his attempt to lift more than half a tonne during the event.

"Pretty casual new world record Elephant Bar deadlift 474kg/1044.9lbs," he said.

"Very happy with day one here at The Arnold Strongman Classic even though 501[kg] will have to wait for another day."

Bjornsson, who received $US72,000 ($101,000) for winning the competition, was presented with a trophy from the event's namesake — former California governor and movie star Arnold Schwarzenegger.

Arnold Schwarzenegger congratulated Bjornsson on his victory. ( Supplied: arnoldsportsfestival.com )

Bjornsson set the previous deadlift world record at last year's Arnold Strongman Classic deadlift, an event which was notable for a graphic viral video of one of his competitor's lifts.

Blood erupted from the nose of former Russian Navy marine Mikhail Shivlyakov as he performed a successful 426kg deadlift.

But the 37-year-old's dramatic effort was still not enough to surpass Bjornsson, who went on to deadlift the then-world record 472kg.