New "Game of Thrones" Season 4 casting updates are being released quite frequently these days, and Sigur Rós is the latest to join HBO's hit medieval fantasy series.

According to Entertainment Weekly, the Icelandic art-pop/rock band has signed on to appear in the highly anticipated fourth season. The exact role of the band, which includes musicians Jón Þór "Jónsi" Birgisson, Georg Hólm and Orri Páll Dýrason, is unknown. However, the band will presumably be playing a song, possibly at a wedding.

EW reports that "Thrones" showrunners David Benioff and Dan Weiss are big fans of Sigur Rós, who are about to embark on a U.S. tour. This isn't the first time that a musical guest has appeared on "Game of Thrones."

Indie bands The National and The Hold Steady have both performed songs inspired by ones that appear in George R.R. Martin's A Song of Ice and Fire saga. The National recorded a version of the "The Rains of Castamere," which was featured in a Season 2 episode and on the soundtrack. The Hold Steady recorded a version of "The Bear and the Maiden Fair," which was featured on the Season 3 soundtrack as well as the show.

Gary Lightbody of Snow Patrol had a cameo appearance in Season 3, and Coldplay's Will Champion was featured as a drummer in the infamous penultimate episode of the third season, which saw the deaths of numerous main characters.

In other Season 4 casting news, relatively low-profile British actors Rupert Vansittart, Elizabeth Webster and Lu Corfield have been cast, according to "Thrones" fan site Winteriscoming.net. Icelandic strongman Hafþór "Thor" Björnsson is also set to play "The Mountain." This is the second time the role has been recast.

The biggest recasting news recently has involved "Treme" and "Nashville" actor Michiel Huisman, who will be replacing Ed Skrein's Season 3 role of Daario Naharis, the love interest of Daenerys Targaryen (Emilia Clarke). "Game of Thrones" returns to HBO in Spring 2014.