Balerion the Black Dread was the greatest of the Targaryen dragons, the last living creature of any kind to have seen Valyria with his own eyes before the Doom. He was already two hundred years old and grown to monstrous size when Aegon the Conqueror rode him out of Dragonstone across the Blackwater, and his fires melted the Iron Throne from the swords of Aegon's defeated enemies.
After Aegon's death Balerion bore Aenys I and Maegor the Cruel, and at the last the boy king Viserys I, whose weight he could scarce feel. By Viserys's reign Balerion had begun to slow, and in 94 AC he died at Dragonstone of old age, the only dragon of the Conquest to do so. His skull, larger than a destrier and black as the dragon himself, was kept in the throne room of the Red Keep until Robert's Rebellion, when it was hidden away.