Confirmed at Comic Con, Season 3 of Game of Thrones will premiere Stateside on March 31 2013. Sky Atlantic will air the following day in the UK.

In addition, the casting of 14 new characters has been announced.

Details (thanks to Winteriscoming)

• Diana Rigg as Lady Olenna Tyrell. Also known as “The Queen of Thorns,” Lady Olenna is the grandmother of Margaery and Loras Tyrell and is, in many ways, the true leader of their powerful family.
• Mackenzie Crook as Orell. A wildling raider, Orell is a “warg” or “skinchanger,” with the ability to enter the mind of an animal and control its actions.
• Clive Russell as Bryndon “The Blackfish” Tully. Known far and wide as “The Blackfish,” Brynden is a famous knight and the uncle of Catelyn Stark. He quarreled bitterly with his brother, Lord Hoster Tully, and the two were estranged for many years.
• Nathalie Emannuel as Missandei. Originally from the peaceful island of Naath, Missandei was sold into slavery as a child, along with her brother. She received education in various languages and became a translator to the slave trader Kraznys in Astapor.
• Kerry Ingram as Shireen Baratheon, the only child of Stannis Baratheon. An avid reader, she escapes her lonely life through myths and stories – her books are her most treasured possessions.
• Paul Kaye as Thoros of Myr. A key member of the outlaw band known as the Brotherhood Without Banners, he is a Red Priest, in service of the Lord of Light, and originally hails from the Free City of Myr, in Essos.
• Thomas Brodie-Sangster as Jojen Reed, a mysterious and enigmatic young man who becomes an important ally to Bran Stark.
• Ellie Kendrick as Meera Reed. The eldest daughter of Howland Reed and a staunch Stark loyalist, Meera and her younger brother Jojen seek out Bran Stark to protect him on his hard journey north.
• Richard Dormer as Beric Dondarrion. Once the lord of Blackhaven and a celebrated warrior, Lord Beric has now become the leader of the Brotherhood Without Banners, a band of vigilante outlaws.
• Kristofer Hivju as Tormund Giantsbane. A famed wildling warrior and chief lieutenant of the “King Beyond the Wall,” Mance Rayder, Tormund is fearsome and strong, with a large build and a beard to match.
• Philip McGinley as Anguy, an extremely skilled archer and key member of the outlaw band known as the Brotherhood Without Banners.
• Tara Fitzgerald as Selyse Baratheon. The wife of Stannis Baratheon, Selyse spends much of her life in seclusion, shut away in a gloomy tower.
• Tobias Menzies as Edmure Tully. The younger brother of Catelyn Stark, Edmure has recently become Lord of Riverrun in the wake of his father’s death.
• Anton Lesser as Qyburn, a former maester of the Citadel, who was stripped of his chain many years ago.