The Mad King is Rhaenyra's father. He was Aerys II Targaryen, the last of the Targaryen dynasty to rule Westeros before Robert Baratheon dethroned him and took control in what is known as Robert's Rebellion. Rhaenyra was his eldest child, born from a previous marriage between Aerys and his first wife Elia Martell. She was named Princess of Dragonstone by her father at birth and upon ascending to the throne after his death, she declared herself Queen of Westeros. Despite being close with her father during childhood, their relationship became strained when he chose another woman to be his queen; this decision caused great anger among many members of House Targaryen loyal to Rhaenyra’s cause, resulting in civil war which ultimately ended with her death at the hands of Aegon II - Aerys' son from his new marriage - leading some to call him the Mad King due to how recklessly he handled matters that led up to it.