Dragons we will not see in House of the Dragon

Quicksilver

Aegon the Conqueror becomes the first king of Westeros. He is succeeded on the Iron Throne by his son Aenys, whose mother was Aegon’s sister-wife Rhaenys Targaryen. Aenys rides the dragon Quicksilver. While Aenys never rode Quicksilver into battle, he rode him frequently while making visits to his vassals around Westeros.

Aenys only reigned as king for five years before dying of illness. His crown was supposed to pass to his son Aegon. However, Aenys’s half-brother Maegor — the son of Aegon and Conqueror and his other sister-wife Visenya — usurped the throne and became the third king of Westeros.

When Aegon learned of Maegor’s betrayal, he and his sister-wife Rhaena made their way to King’s Landing to reunite with Rhaena’s dragon Dreamfyre. At the same time, Aegon bonded with his father’s old dragon Quicksilver. The pair of them fled the capital on dragonback.

Eventually, Aegon, called the Uncrowned,  assembled a sizable host of 15,000 Rivermen and Westermen to win back his father’s throne. While making their way to King’s Landing, Aegon’s army met Maegor’s. Although Aegon had Quicksilver, Maegor rode Balerion, then the world’s largest and oldest living dragon. Similar to how Vhagar easily dispatched of Arrax in Episode 10 of House of the Dragon, Balerion overwhelmed the smaller Quicksilver and ripped one of its wings off. Quicksilver and Aegon the Uncrowned plummeted to the ground and died on impact.

This was the first time that dragon fought dragon in the skies above Westeros. Maegor the Cruel went on to rule the seven kingdoms until his mysterious death five years later.