Ser Jaime Lannister is a knight of the Kingsguard, the son of Tywin Lannister, twin brother of Queen Cersei Lannister, and older brother of Tyrion Lannister. Previously he served in the Kingsguard of Aerys II Targaryen and, infamously, he betrayed and killed Aerys during the Sack of King's Landing, earning him the sobriquet "The Kingslayer".