I read in an article that the following characters are set to be cast in the new greenlit season (which will be roughly the first half of the 3rd book, A Storm of Swords)
– Mance Rayder: We’ve heard about him all season. A former member of the Night’s Watch who became the “King Beyond the Wall,” the leader of the Wildlings.
– Daario Naharis: A confident and seductive warrior.
– Jojen Reed; Meera Reed: A teenage brother and sister duo with special insights.
– Edmure Tully: A brash young member of the Tully family.
– Ser Brynden Tully (The Blackfish): Catelyn Stark’s uncle.
– Lady Selyse Florent: Stannis Baratheon’s wife.
– Shireen: Stannis’ daughter.
– Olenna Redwyne (The Queen of Thorns): Margaery Tyrell’s sharp-witted grandmother.
– Beric Dondarrion: A skilled knight who is the leader of the outlaw group Brotherhood Without Banners.
– Thoros of Myr: A red priest who follows the same religion as Melisandre.
– Tormund Giantsbane: A Wildling raider.
Article found here:
http://insidetv.ew.com/2012/05/29/game-of-throne-season-3-cast/
I also recall at one point that Vargo Hoat will also be cast in the season.
– Mance Rayder: We’ve heard about him all season. A former member of the Night’s Watch who became the “King Beyond the Wall,” the leader of the Wildlings.
– Daario Naharis: A confident and seductive warrior.
– Jojen Reed; Meera Reed: A teenage brother and sister duo with special insights.
– Edmure Tully: A brash young member of the Tully family.
– Ser Brynden Tully (The Blackfish): Catelyn Stark’s uncle.
– Lady Selyse Florent: Stannis Baratheon’s wife.
– Shireen: Stannis’ daughter.
– Olenna Redwyne (The Queen of Thorns): Margaery Tyrell’s sharp-witted grandmother.
– Beric Dondarrion: A skilled knight who is the leader of the outlaw group Brotherhood Without Banners.
– Thoros of Myr: A red priest who follows the same religion as Melisandre.
– Tormund Giantsbane: A Wildling raider.
Article found here:
http://insidetv.ew.com/2012/05/29/game-of-throne-season-3-cast/
I also recall at one point that Vargo Hoat will also be cast in the season.