Not only was Balerion the biggest dragon Westeros had ever beheld, but he was also the most powerful, the most feared. He was the God of Dragons. Balerion, the Black Dread, was two hundred years old when he died. Even Vhagar, who lived at the same time Balerion had, never reached his full size.

His name was after an ancient god in Old Valyria. It was there that he was born, only a hatchling, and when Daenys the Dreamer, daughter of Lord Aenar Targaryen, had a prophetic dream, assisted by visions, that Valyria would fall. Foreseeing the Doom, Daenys convinced her father to leave, saving the entirety of Targaryen House from ultimate oblivion.

Balerion was one of the five dragons Aenar Targaryen brought with him when he fled to Dragonstone to survive the Doom of Valyria. However, it wasn't long before four of the dragons died, and Balerion became the last creature to have seen the Freehold in its prime.

During his life, he had four riders; Aegon (who he bonded with), Maegor (also bonded with), Aerea (flew off with her on his back, and weren't seen for almost a year. When Balerion returned to King's Landing, Aerea died within hours) and Viserys (who rode him towards the end of his life three times around King's Landing).

Balerion's first two riders used him to conquer kingdoms, burn down cities and remind people of the strength of House Targaryen. The third had used him to escape her life and the last, well, he had done it to prove he was a worthy choice to be King.

In appearance, Balerion had black scales and wings and a black flame with swirls of red. With his fire, he could melt steel and stone, and turn glass into sand. His wingspan was so large that his shadow could engulf entire towns when he passed overhead. His teeth were as long as swords, and his jaws were large enough to swallow aurochs whole.

When the Targaryen's ruled, the skulls of the dragons were hung on a wall in the Red Keep's throne room. And when they did not, the skulls were kept in the dark, dank cellar of the Red Keep.