Ser Gregor of House Clegane, the Mountain That Rides, the Knight of Clegane’s Keep, Protector of Cersei Lannister, brother of The Hound, the head-exploder, the Zombie of Westeros, the Executor badly in need of eye cream.

And now: brand ambassador for Reign Total Body Fuel.

Hafþór Júlíus Björnsson, who often goes by the moniker Thor, is best known for playing the feared yet revered knight The Mountain on Game of Thrones, currently airing its final season. But this week he’s waging a different war. Standing in New York City’s Greeley Square, Björnsson wears a black tank top and matching pants while clenching a plastic shield with a silver helmet insignia. Sitting beside him on a makeshift throne built of energy drink cans is not his loyal queen Cersei of House Lannister bur rather former WWE Total Diva Natalie Eva Marie, now of House Reign.

The duo is flanked by an army of buff models and workout instructors probably on their lunch breaks from Barry’s Bootcamp or SoulCycle. They’re ready for battle—and today that’s convincing you to purchase Reign Total Body Fuel.

The new workout energy drink by Monster promises increased concentration, electrolytes and reduced fatigue. It makes sense Björnsson would partner with a product with “Total Body Fuel” right there in the name. He quite literally epitomizes the totality of the human form.

The Icelandic native is the reigning World’s Strongest Man (He can do a 10-rep, 770-pound axle deadlift). He weighs 450 pounds and is 6-foot-9. He’s a hulking presence, making him ripe for fan photos and more than a little intimidating to interview.

Björnsson , who grew up outside Reykjavik, hasn’t always been so big. His first successes came on the basketball court, where his height and slender frame made him a towering yet agile presence. That is until two severe broken ankles in two years ended his career. It would’ve been impressive enough: small-town boy leaves family farm for an illustrious yet short-lived Division I basketball career.

But soon after, he met former four-time World’s Strongest Man Magnús Ver Magnússon , bulked up, and found a new calling on the Icelandic bodybuilding circuit. Björnsson entered his first World’s Strongest Man competition in 2011 and finished 6th. It’s the lowest he’s ever placed.

“I haven’t lost a competition since 2017 actually,” Björnsson says, surprisingly soft-spoken for his stature. “I won everything last year and everything this year. It’s going well for me.”

To his word, Björnsson is the current reigning World’s Strongest Man, beating out longtime rival Brian Shaw of America two years ago and holding the title ever since. They’ll face off again in a month for the 2019 title in Bradenton, Florida. Björnsson , who as Ser Gregor Clegane has killed Faith Militants, stabbed his hefty sword straight through King’s Landing commoners, and caused others to faint by simply leaning forward, isn’t worried about his odds. “I’m going to the 2019 competition to defend the title,” he said.

But right now, he’s focused on press tours. In addition to Reign Total Body Fuel, Björnsson is knee-deep in Game of Thrones promotion. He and his 5-foot-2 wife Kelsey Henson walked the Season 8 New York premiere red carpet in early April. He wore a teal, fitted blazer and black bow tie and gave The Rock a run for his money as Hollywood’s best-dressed bodybuilder.

Expectedly, he’s tight-lipped about the final season. HBO is the only entity that could take him down, so he’s following strict no-spoiler orders. Though he’s happy to talk about the iconic battle against Oberyn Martell, played by hot actor Pedro Pascal. Like most of his fans, it’s also his favorite kill scene. “It was my first season. Everything about it—the training that went into it, the location, the people I shot with, the directors—I just loved shooting that scene,” he says.

Since the ill-fated battle where he dies after being sliced by a sword doused in venom, The Mountain has become an ominous presence in Westeros. Hand of the Queen Qyburn resurrects him from death, but the man behind the full-body armor remains a mystery—save for a single Season 6 scene revealing his mangled, discolored face while torturing Cersei’s prisoner the Unella, otherwise known as the “shame, shame” bell lady.

How did Qyburn resurrect The Mountain? Is he Westeros’ first zombie? Why are his eyes bloodshot but his skin blue? Björnsson will not be providing answers today. “I’m something,” he says, refusing to give an inch. “I’m coming from death. Not much more I can really say on that.”

He’s also equally coy when speaking about real-life controversy. This week, his admission to having previously used steroids, stated during a 2017 ESPN E:60 special, resurfaced online. “Yes, I have,” he said in the documentary. “When you want to be the best, you do whatever it takes.” When the reporter pressed him, he remarked, “Can we just skip those questions?”

Now two years later, he’s won’t clarify his statement or declaratively state that his steroid use is fully in the past. Maybe that’s by design. Björnsson is just doing as he always has: His body speaks for itself.

“I’ve been competing at the World’s Strongest Man competition for the past eight years,” he told The Daily Beast. “I never failed a drug test, so that really answers your question.”