The moment 'Game of Thrones' season 3 cast Coldplay drummer Will Champion in a cameo role, we had some idea where the musician would pop up in the season. Now, in what's become something of a unique tradition for the series, 'Game of Thrones' season 4 has tapped Icelandic band Sigur Rós for yet another top-secret cameo, though admittedly one with far-less speculation around it.

Entertainment Weekly revealed the news, specifying that Jón Þór “Jónsi” Birgisson, Georg Hólm and Orri Páll Dýrason are currently shooting an appearance on the HBO fantasy drama's set in Croatia, without revealing the nature of the appearance, or a potential song cover. 'Game of Thrones' showrunners David Benioff and Dan Weiss are reportedly longtime fans of Sigur Rós, often listening to their music while shooting in Iceland.

Similarly, 'Game of Thrones' employed The National in season 2 for a cover of "The Rains of Castamere," as well as The Hold Steady in season 3 for “The Bear and Maiden Fair." In addition to Will Champion, Snow Patrol's Gary Lightbody has appeared in the past as a Bolton soldier as well.

While we wait for ‘Game of Thrones’ season 4, HBO has cast in known roles Roger Ashton-Griffiths as Mace Tyrell, Indira Varma as Oberyn’s lover Ellaria Sand, and 'Sherlock' star Mark Gatiss as Tycho Nestoris. ‘Banshee‘ star Joseph Gatt will appear in a role speculated to be that of Wildling chieftan Styr, Magnar of Thenn, while ‘Treme”s Michiel Huisman will replace Ed Skrein as Daario Naharis, and Hafthor Julius Bjornsson will take over the role of Gregor “The Mountain” Clegane from Ian Whyte, among other recastings. Previous season characters Lysa Arryn (Kate Dickie), Ser Alliser Thorne (Owen Teale), Rorge (Andy Beckwith) and Janos Slynt (Dominic Carter) will likely all return, among others.

We'll keep you posted on Sigur Rós' guest role, but what do you thing 'Game of Thrones' season 4 will do with the Icelandic group?

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