Until Daenerys Targaryen hatched three supposedly fossilized eggs in the first season finale on Game of Thrones, dragons had been extinct for over 150 years. As she now faces a war in Westeros for control of the Iron Throne, the legacy of the Targaryens who came before her, who also had three dragons, makes her seem invincible. But are they? With the chances rising Dany will be riding one into battle soon, let's explore how dragons can be killed on Game of Thrones.
Let us note that prior to the Targaryens landing in Westeros in 3 BC, the Doom of Valyria had actually done a huge number on the population of dragons. Hundreds upon hundreds of the beasts were killed when the 14 Fires erupted in a volcanic cataclysm that destroyed most of the Valyrian population, as well as their capital city. Of those dragons who were alive at the time, only five survived the Doom -- the five that the Targaryens had taken with them when they fled to Dragonstone, having seen prophetic visions of the coming Doom.
Four of those dragons were already old and died on Dragonstone prior to Aegon's Conquest. But they left behind eggs, from which hatched Meraxes and Vhagar, who were ridden to Westeros along with the surviving Balerion from Valyria to help the Targaryens take the continent.
How Most Dragons Die
Up until the Doom of Valyria, most dragons died of old age -- the oldest is known to have lived for 200 years. Though they are a violent species, they have a "reasonably high intelligence." They also have the ability to form strong emotional bonds, especially with their riders, whom they select with care.
It is said dragons know when their riders die, and that they never allow anyone else to mount them while their rider is alive. This goes for the rider too -- no dragon will allow someone to mount them who is another's rider while their dragon lives. They do pick new riders after their previous one is dead though.
Dragons Killed By Other Dragons
Since the Doom of Valyria, only 27 dragons are recorded to have lived, not including Dany's current brood. Of those 27, nine died of natural causes. The other 18 were killed in battle, ten of which were killed by another dragon.
Though dragons are supposedly "fire made flesh" this does not make them impervious to fire. Their hides toughen as they age, so young dragons are especially vulnerable to the flames of an attacking dragon. All of the 10 who died at the claws of another dragon did so during the time known as "The Dance of Dragons," aka, the Targaryen Civil War.
As for the other eight who were killed by humans:
One of the three dragons who was part of Aegon's original conquest, Meraxes, was the medium sized of the three, with silver scales. Her rider was Rhaenys.
She was killed by a scorpion bolt through the eye, during the First Dornish War, in 10 AC, as Aegon attempted to foolishly conquer Dorne. The shot was lucky and brought down both dragon and rider, neither of whom survived. Her skull is one of those which decorated the Targaryen throne room, which Robert moved to the Dragon Pit.
She is the only dragon to be killed by a human on the battlefield that was not part of the Dance of Dragons.
Stormcloud was young male dragon, who was bonded to Aegon III Targaryen, also known as Aegon the Younger. Stormcloud was badly wounded by several cross-bolts and scorpion-bolts during the skirmish known as The Battle of the Gullet during the Dance of Dragons. He died within an hour of arriving home.
A male dragon ridden by Prince Jacaerys, they rode out to wreak vengeance for Stormcloud during The Battle of the Gullet. Jacaerys rode Vermax too close to the ships carrying the enemies and got his dragon hooked by their ropes and drawn down into the water, where both rider and dragon died from too many cross-bolts, too much water, and a couple of wrecked ships on top.
Please, no one tell Euron about this.
The last five dragons who died at the hands of man did so during the incident known as the Riot of King's Landing at the end of the Targaryen Civil War. A mob descended upon the Dragon Pit where four dragons lay chained up helpless and murdered them.
A young male dragon bound to Prince Joffrey, Tyraxes was too young to see battle. The only action he saw was the night the mob came, lead by the crazed one-armed man known only as "The Shepherd" who egged on the crowds to kill the dragons and make their country great again, or something.
Tyraxes almost survived the riot, as the corpse pile prevented the mob from getting to his from the front passage. But when they came back through the back passage he became bound up in his own chains and was stabbed to death.
Another young she-dragon, Shrykos was bound to Prince Jaehaerys. Like Tyraxes, she was never part of any battle- -- in fact, she was so young, she had never been ridden. Her death is credited to Hobb the Hewer, a woodsman, with a giant axe, which he slammed into her skull repeatedly.
The fourth of and last of those dragons who were chained in the Pit, Dreamfyre was much older. A mature she-dragon, she was originally the mount of Princess Rhaena Targaryen. At the time of the Dance, she had become bounded to Princess Helaena.
She managed to break free of her restraints, only to crash into the huge domed glass and stone ceiling, which then collapsed back on top of her and the mob, killing both her and many of them. The ceiling has never been repaired.
A she-dragon bound to Rhaenyra Targaryen, known as the Half-Year Queen. Syrax wasn't in the Dragon Pit, but up at in the Red Keep with her rider when the riots began. Hearing the cries of her brothers and sisters as they were slain, she escaped the Keep's walls and flew to the Pit to help rescue her kin.
She was an old, fat dragon who hadn't hunted in decades by the time the war rolled around. Prince Joffrey (Tyraxes' rider) tried to mount her as she left, but she shrugged him off mid-flight, killing him instantly. When she landed she was dragged down by the rioters and murdered.
The moral of this is, while cross-bolts and ropes and a few lucky shots can take down dragons, humans are most deadly to them in mob form.