Jaehaerys Targaryen

Eldest son of King Aegon II and Queen Helaena, born the elder of twins with his sister Jaehaera in 121 AC, and named heir to the Iron Throne as Prince of Dragonstone. He was bound to a hatchling dragon, Morghul, and betrothed in the cradle to his twin after the fashion of old Valyria. When the Dance of the Dragons began and Prince Lucerys Velaryon was slain above Shipbreaker Bay, Daemon Targaryen hired two cutthroats out of the gutters of King's Landing, called Blood and Cheese, to answer son for son; they stole into Maegor's Holdfast by the secret passages of the Red Keep and took the queen and her children in her bedchamber. Made to choose which of her boys would die, Helaena named the younger Maelor in hope of sparing the heir, whereupon Blood sawed off Jaehaerys's head with a single hard stroke while Cheese held her fast, the prince six years old.