'Omg, Is That the Mountain?': Netizens Couldn't Believe It Was the Same Gregor Clegane From 'Game of Thrones' Following His Dramatic Weight Loss – Photos

Best known for portraying one of television's most intimidating characters, the actor looked almost unrecognizable following his striking transformation. The before and after photos are waiting for you at the end of this article.

He towered over nearly every character in "Game of Thrones" as the brutal Ser Gregor Clegane, better known as the Mountain, but years after leaving Westeros behind, Hafþór Júlíus Björnsson had people doing double takes for a very different reason.

Although the Mountain first appeared on the HBO fantasy series with Conan Stevens in season one before Ian Whyte took over in season two, the role was recast again when the character's storyline expanded significantly.

Beginning with season four, Björnsson stepped into the part and quickly became the definitive face of the fearsome knight. Standing 6-foot-9 and already well known in the world of strongman competitions, he brought the immense size and physical presence the role demanded.

His time on the series included some of its most unforgettable moments, from the Mountain's brutal clash with Oberyn Martell, played by Pedro Pascal, to the character's resurrection into a monstrous Kingsguard warrior.

Unlike many cast members who landed their roles through traditional auditions, the actor's path to the show came about because the production team specifically sought him out while filming in Iceland. He recalled:

"I was in Iceland, as you know, training for Strongman, and they were filming currently in Iceland. They had heard about me, and they reached out to me, and therefore I did my audition in Iceland. And I got the part."

Away from acting, Björnsson continued building his reputation as one of the world's strongest athletes, setting multiple weightlifting records, including a raw deadlift of 510 kilograms, or 1,124.36 pounds.

However, the physique that helped define both his athletic career and his on-screen persona has changed dramatically over the past few years. Over roughly 18 months, Björnsson shed approximately 121 pounds as he shifted his focus from maintaining his strongman size to achieving a leaner physique.

Speaking previously about the transformation, he explained that consistency played a key role. Rather than making drastic changes overnight, he gradually adjusted his eating habits through what he described as "baby steps," reducing portion sizes, eliminating sugary drinks, and making small dietary tweaks over time.

His current routine revolves around five protein-rich meals each day, featuring foods such as eggs, chicken, beef, salmon, rice, potatoes, greens, skyr, peanut butter, and whey protein. While his diet remains disciplined, Björnsson has also said he allows himself one cheat meal each week. He explained:

"You can't be a robot. We're all human, we all crave things. It's OK to go off the diet as long as you stick to it six days a week, or however you do it."

At the same time, he acknowledged that approach may not suit everyone, noting that his personal preference is to eat healthy most of the week before enjoying a more indulgent meal.

As photos of the former strongman circulated online, many were stunned by just how different he looked after the dramatic weight loss. "Omg 😱 is that the mountain????" one person commented, while another asked, "That him now [sic]?? For real?"

Others also struggled to recognize him, with one writing, "If it weren't for the tattoos and that look on your face I wouldn't have believed it was you. Good job!! Looks good."

Not every reaction was complimentary, however. Some admitted they preferred Björnsson's previous appearance, with one person commenting, "Not sure how I feel about this. Too skinny. You can't call yourself Thor anymore."

Another shared, "Sorry but I prefered your old one personnaly.. but anyway congratulation and I respect totally your choice [sic]." Meanwhile, another remarked, "After all that weight turns out u [sic] weren't that muscular."

Whether they praised his dedication, questioned his slimmer physique, or simply struggled to recognize him, the reactions underscored just how dramatic Björnsson's transformation has been since his days portraying the Mountain in "Game of Thrones."

Scroll below to see photos of the Icelandic strongman before and after his remarkable weight loss.

Before

After