Though a slew of actors were recently announced at Comic Con as new additions to HBO's Game of Thrones third season cast, one of the biggest roles remained a mystery -- that of Mance Rayder, known as the "King Beyond the Wall."  Though exhaustive speculation and fancasting has taken place since the series' first began regarding who might play the popular character, it was revealed today that Irish actor Ciarán Hinds (Tinker Tailor Soldier Spy) will take the role.Mance is connected to the story of Jon Snow (Kit Harington), and is leader of the Wildlings -- a singular presence who has united the forces beyond the Wall together to march south into Westeros, something that the now scattered and beleaguered Night's Watch has been preparing for with dread for years.  For more on the casting, hit the jump.game-of-thrones-season-2-kit-haringtonMany HBO fans may remember Hinds' fantastic turn as Julius Cesare on Rome, and while a great number were hoping his charming Rome castmate James Purefoy (who played Marc Antony) would take the role of Mance, EW tells us Purefoy was unavailable due to a scheduling conflict with Fox's The Following.British actor Dominic West (The Wire) was also approached for the role but turned it down because of family reasons (admirable of course, though reading the filming timeline he was given it seems someone didn't do a very good job of explaining exactly how much of that filming bloc he would actually be required for).Still, the outcome has turned out fine as Hinds is a truly great actor who should embody the cunning role of Mance perfectly.  Hinds joins another Rome alumnus on set -- Tobias Menzies (who played Brutus), who has already been cast as Catelyn Stark's younger brother Edmure.The third season of Game of Thrones is set to return in March of 2013.