"Game of Thrones" season 4 spoilers reveal a first look photo of The Mountain filming on set in Dubrovnik, Croatia. Check out the photo here!

Icelandic actor Hafthor Julius Bjornsson posted a new photo to his Instagram, revealing to fans the first look at Bjornsson in costume as Gregor "The Mountain" Clegane. The photo shows The Mountain wearing full armor and carrying a sword, but unlike the temperament of the brutal brother to Sandor "The Hound' Clegane (Rory McCann), Bjornsson is wearing a big grin on the "Game of Thrones" season 4 set, while filming in Dubrovnik.

Bjornsson captioned the spoiler photo: "Game of thrones season 4 #dubrovnik #got #mountain#croatia #sword #big #lovethis"

Bjornsson is the third actor to play The Mountain, The Hollywood Reporter notes. Conan Stevens first played The Mountain for two episodes in "Game of Thrones" season 1, and then Ian Whyte took over the role for season 2.

Hypable recaps The Mountain's cruel past: Littlefinger (Aidan Gillen) tells Sansa (Sophie Turner) in season 1 of "Game of Thrones" the story of how the Mountain shoved his little brother Sandor's head into the fire and burned half his face away, after he caught the younger boy playing with one of his toys.

HBO has also cast multiple newcomers for new roles in season 4 of "Game of Thrones," including Joel Fry as Hizdahr zo Loraq, Roger Ashton-Griffiths as Mace Tyrell, Pedro Pascal as Prince Oberyn Martell, Indira Varma as Oberyn's lover Ellaria Sand, and 'Sherlock' star Mark Gatiss as Tycho Nestoris, ScreenCrush reports. 'Banshee' star Joseph Gatt will appear in a role speculated to be Wildling chieftan Styr, Magnar of Thenn, while 'Treme"s Michiel Huisman will replace Ed Skrein as Daario Naharis.

"Game of Thrones" season 4 will premiere spring 2014.