The title Prince or Princess of Dragonstone was given to the heir apparent to the Iron Throne during the Targaryen dynasty. The heir apparent's seat was the castle of Dragonstone located on the island of the same name.
While King Aegon I Targaryen raised his heir, Prince Aenys, with him at King's Landing, his younger son Maegor was raised by his mother Visenya on Dragonstone. In time, he became known as the "Prince of Dragonstone". Maegor remained the Prince of Dragonstone during the earlier years of Aenys's own reign, even though Aenys had heirs of his own. After Maegor was exiled, Aenys established "Prince of Dragonstone" as a formal title by appointing it to his eldest son and heir, Prince Aegon. His younger son, Jaehaerys I Targaryen, eventually continued using "Prince of Dragonstone" as a formal title. The only Targaryen King who might not have named a Prince of Dragonstone was King Aegon II Targaryen, who fought a war against his sister Rhaenyra, who controlled Dragonstone at the time. Prince Rhaegar Targaryen (pictured), the eldest son of King Aerys II Targaryen, was the last confirmed Prince of Dragonstone.
The Targaryen dynasty ended with Robert's Rebellion. The new royal house, House Baratheon of King's Landing, did not continue the use of the formal title. Instead, King Robert I Baratheon granted Dragonstone to his younger brother, Stannis, as his personal seat. He now rules Dragonstone as the Lord of Dragonstone, a title which had also been used by the Targaryens prior to Aegon's Conquest.
However, King Aerys II's youngest son, Viserys, had been crowned on Dragonstone after his father's death, prior to the castle's fall. As his sole heir, his sister Daenerys has claimed the title "Princess of Dragonstone". Read more...