Sansa Stark is the elder of Ned Stark’s two daughters. She was formerly betrothed to king Joffrey, but was married to Tyrion instead. She fled from King’s Landing after Joffrey’s assassination and is now living in the Eryie with Petyr Baelish, who was briefly married to her aunt and is now the Lord of the Vale.
Samwell Tarly is a cook at the Night’s Watch and quickly became a close friend of Jon Snow’s.
Roose Bolton is the ruthless leader of the Dreadnaught, a city in the north. He was a former bannerman of the Starks, but turned on them and helped orchestrate the Red Wedding. In return he was declared the lord of all the north.
Robb Stark was the eldest son of Ned Stark and the short-lived King of the North during the rebellion. He was killed at the Red Wedding.
Rickon Stark is the youngest Stark. He fled with a wildling servant and his wolf, Shaggydog, when Winterfell was invaded. We have no idea where he is.