Cersei Lannister, rarely called Cersei Baratheon, is a major character in the first and second seasons. She is played by starring cast member Lena Headey and debuts in the series premiere. Cersei is the widow of King Robert Baratheon and Queen Regent of the Seven Kingdoms. She has installed her son Joffrey Baratheon on the Iron Throne under the false claim that he is a legitimate son from her marriage but he is actually the product of her incestuous relationship with her brother Ser Jaime Lannister. While acting as the regent, she clashes with the acting Hand of the King Tyrion Lannister and has troubles controlling King Joffrey's erratic behavior.