Jon Snow: For all his life, Jon Snow has believed he is a bastard born of Ned Stark — the beloved lord in the north of Westeros killed in season one — and an unknown woman. Ned raised Jon with his other children until Jon decided to join the protectors of the realm called the Night’s Watch.
He rose through the ranks, did some controversial but humane stuff, was killed by his own men and then brought back to life. At the start of season eight he is considered King in the North, but he has also pledged fealty to Daenerys Targaryen.
Though he doesn’t know it yet, Jon’s parents were actually Lyanna Stark — Ned’s sister — and Rhaegar Targaryen, making him Daenerys’s nephew and possibly the rightful heir to the Iron Throne because he isn’t actually a bastard. Lyanna and Rhaegar were married during the war, so he would be the legitimate heir of the Mad King Aerys’s heir, Rhaegar. This is sticky because he and Daenerys, who believes she is the rightful heir, hooked up at the end of season seven and seem headed for a relationship or marriage.
Daenerys Targaryen: Daenerys is the daughter of the Mad King Aerys and the last surviving Targaryen — or so she thinks. She brought forth three dragons in season one, the first anyone had seen in more than 100 years, and she’s spent the series using them and her followers to conquer cities in Essos and free slaves. Now she’s set her sights on her ultimate goal: the Iron Throne, though she is helping to defeat the army of the dead first.
Cersei Lannister: Cersei Lannister was King Robert’s wife and the mother of his “children” — heavy quotation marks because her three kids were actually the result of incest with her twin brother Jaime. After her husband and three kids died, Cersei took the Iron Throne for herself.
She’s done a lot of evil stuff during the series, most notably blowing up a place of worship with a ton of people in it including her daughter-in-law. She claimed to be pregnant at the end of season seven with Jaime’s child, but many viewers are skeptical. She also lied to Jon and Daenerys, telling them she would fight the army of the dead while she actually made plans to secure an army to help her keep the throne in the south.
Jaime Lannister: Jaime Lannister is an infamous knight in the kingdom most known for killing King Aerys, despite being pledged to protect him. It’s significantly more complicated than that, but for the purposes of season eight, it’s most important to know that he was devoted to his sister/lover Cersei until the end of season seven.
She refuses to help fight the White Walkers coming to ransack the realm and has instead holed up in her castle. This caused Jaime to finally abandon her — the other evil stuff somehow wasn’t enough — so for season eight, he is riding north, where he intends to join the fight against the army of the dead.
Tyrion Lannister: The younger brother of Cersei and Jaime Lannister, Tyrion is a dwarf with a prowess for politics. He is estranged from Cersei and, to an extent, Jaime after Tyrion killed their father in season four and fled to Essos. He teamed up with Daenerys overseas and has become one of her most important advisers.
Sansa Stark: The oldest surviving trueborn child of Ned Stark, Sansa has been acting ruler of the North for a season while Jon was away. She started the series as a little girl dreaming of becoming a queen but after a lot — A LOT — of suffering, she is now a powerful political player.
Arya Stark: The second oldest surviving trueborn child of Ned Stark, Arya started the series as a tomboy eager to keep up with her older brothers. Now, she’s a trained assassin who can wear other people’s faces to disguise herself.
Bran Stark: The last surviving son of Ned Stark, Bran has magical powers that allow him to enter the minds and bodies of animals and see backward and forward in time. He has become a magical being called the Three-Eyed Raven and essentially shed his humanity and identity by season seven.