9. Meraxes
This dragon was actually mentioned on the show, although it’s possible some viewers were distracted by the nakedness. It’s in the scene where Viserys Targaryen, naked in a tub with Doreah, names several dragons, some of them from the books, some made up then and there. His delivery of the name “Meraxes” is somewhat compromised, but it’s in there.
Anyway, Meraxes, Rhaenys Targaryen’s dragon, is a formidable beast with gold and silver scales. It’s bigger than Vhagar, Visenya’s dragon, while not quite as big as Balerion, the dragon of Aegon I the Conqueror, Rhaenys’s brother and husband.
Meraxes took part in the Conquest of Westeros and played his part in the Field of Fire alongside Balerion and Vhagar. During the Battle of the Last Storm, Meraxes unleashed his fire on Argilac the Arrogant Durrandon, his vanguard and his personal guard. This helped the Targaryens secure a victory and paved the way for the establishment of House Baratheon.
The real question here is if Meraxes shouldn’t rank higher. Meraxes is only in ninth place because he died because of something as mundane as a bolt from a scorpion to the eye during an unsuccessful attempt to conquer Dorne.