Balerion, called the "Black Dread", was one of Aegon I's three dragons that he used to conquer much of Westeros during the War of Conquest. Balerion is the largest of all the Targaryen dragons, and had jaws big enough to swall a mammoth whole. Singers named him after an ancient god, as they did with the other two original dragons. He died at around 200 years of age, during the reign of Jaehaerys I.
References and Sources
- A Game of Thrones, Chapter 13, Tyrion