Hafþór Júlíus Björnsson/Instagram Hafþór Júlíus Björnsson and Kelsey Henson
The Mountain is a dad!
Hafþór Júlíus Björnsson — best known for his role as Gregor "The Mountain" Clegane on Game of Thrones — and wife Kelsey Henson welcomed their first child together, a baby boy, on Saturday, the couple announced on Instagram.
"Our beautiful baby boy made his grand entrance into the world at 11:19 AM on September 26th 2020 after a short and intense six hours. 3530 grams and 52 cm. The birth was the most powerful, life changing, empowering thing I’ve ever done in my entire life. We are all doing well and settling in at home as three!" the new mom shared on Sunday.
The actor also shared the story of their son's birth. "After an extremely hard 2 hours and 19 mins of pushing our healthy, strong, beautiful boy arrived weighing 3530 grams, 52 cm long," he said. "To finish the most beautiful, awe inspiring labour was the most wonderful phone call to my daughter to introduce her to her new little brother."
Björnsson is also dad to daughter Theresa Líf, whom he shares with his ex-girlfriend Thelma Björk Steimann.
Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.
Björnsson announced Henson's pregnancy in April, alongside photos from their "gender reveal" party. The actor, 31, and his wife learned the sex of their baby by popping a large black balloon, from which burst blue confetti.
"Swipe right to see gender of the mini me! 😱," Björnsson wrote alongside a series of photos that showed the then-parents-to-be beaming with joy.
Björnsson and Henson (who are 6 ft., 9 in., and 5 ft., 2-in., respectively), showed off their excitement with their hands in the air, smiling from ear to ear.
In another photo, the two shared a sweet kiss and were seen looking lovingly at one another after finding out the big news.
Björnsson and Henson celebrated their son on the way in early August at a sweet baby shower full of gifts and fun games — which the actor joined in on!
"My beautiful wife is 31 weeks + 2 days pregnant! 😍 I couldn't be more proud of you @kelc33 ❤️," he captioned a photo of the pair, in which he cradled her baby bump lovingly while she wore a sash reading "Mom to Be."
The GoT star and Henson tied the knot in October 2018 in his native Iceland.
"It is with great pleasure that I now get to call Kelsey Morgan Henson my wife!" Björnsson captioned a photo of himself holding his bride up on their wedding day.