One of the most important new roles on Game of Thrones for season 4 has officially been cast.

Russian actor Yuri Kolokolnikov will play Styr, the Magnar of Thenn according to a Tuesday report by Entertainment Weekly. The actor, who is much more famous in Russia, is playing one of the more significant characters from the A Song of Ice and Fire book series on which the show is based.

Styr is the leader of Thenn, a beastly tribe from North of the Wall. In A Storm of Swords, the third book in the saga, Styr helps Mance and the wildlings lead the attack on Castle Black against the men of the Night's Watch. Assuming the series goes along with the plot of the book, season 4 should involve the tribes moving to invade and attack Westeros.

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It was originally reported that actor Joseph Gatt would be playing Styr, the Magnar of Thenn, but that information was based on a rumor by IMDB. However, Gatt is still going to be on Game of Thrones in season 4, according to The Hollywood Reporter.

Kolokolnikov joins a number of guest stars who are slated to appear on the upcoming season of Game of Thrones. Other guest stars include Struan Rodger as the Three-Eyed Raven, Roger Ashton-Griffiths as Mace Tyrell (father of Margaery and Loras) and the Icelandic band Sigur Ros.

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Game of Thrones does not have a scheduled premiere date yet but it is expect to return for season 4 in spring 2014.