The "Mad King" in Game of Thrones is King Aerys II Targaryen. He was the sixteenth (or seventeenth, depending on the source) Targaryen to rule from the Iron Throne and is infamous for his descent into madness during his reign

. Initially a charismatic and capable ruler, Aerys II became increasingly paranoid and cruel, exhibiting erratic behavior such as burning his enemies alive and ordering the destruction of King’s Landing with wildfire during Robert's Rebellion

. His madness was partly attributed to his incestuous Targaryen lineage and personal losses, as well as possible prophetic fears shown in the prequel House of the Dragon that may have worsened his paranoia

. His reign ended when Jaime Lannister, a Kingsguard sworn to protect him, killed him to prevent the king from burning the city and its inhabitants

. Aerys II was the father of Daenerys Targaryen and her brothers Rhaegar and Viserys. His tyranny and eventual downfall sparked Robert's Rebellion, which led to the end of Targaryen rule and the rise of Robert Baratheon as king

. In summary, the Mad King is:

• Name: Aerys II Targaryen
• Title: King of Westeros, last Targaryen to rule the Iron Throne
• Known for: Cruelty, paranoia, madness, ordering people to be burned alive
• Fate: Killed by Jaime Lannister during Robert's Rebellion to stop him from destroying King’s Landing
• Legacy: His reign's end marked the fall of House Targaryen and set the stage for the events of Game of Thrones