Melisandre, more commonly know as the Red Woman, is a priestess of the Lord of Light and the lover/advisor to Stannis Baratheon. She has exhibited magical ability many times, including giving birth to shadow assassins to kill Stannis’ younger brother, Renly.
Margaery Tyrell was married to king Joffrey for only minutes before he was killed. Now, she means to make Tommen her husband as well. She is manipulative and beautiful and always tries to get public opinion on her side.
Petyr Baelish is a self-made man. He worked his way up from nothing to becoming a successful brothel owner and the nation’s Master of Coin. He is also manipulative and knows everyones’ secrets. Baelish orchestrated the killing of King Joffrey, killed his wife, Lysa Arryn, and is now the Lord of the Vale.
Jorah Mormont was banished from Westeros after he was caught selling slaves. Now, living on the other side of the Narrow Sea, Jorah is one of Daenerys Targaryen’s chief advisors and guards. He used to spy for the king of Westeros, but stopped when Daenerys started gaining power.
Jon Snow is the bastard son of Ned Stark, conceived during Ned and Robert Baratheon’s rebellion that overthrew the Mad King Aerys Targaryen. He has risen through the ranks of the Night’s Watch and spent time undercover amongst the wildlings.