Morghul was a juvenile dragon bound to Princess Jaehaera Targaryen but never ridden by her.
Rhaenyra Targaryen and her blacks took King’s Landing from Aegon II Targaryen and his greens during the Dance of the Dragons. Princess Jaehaera Targaryen, Morghul’s owner, was successfully whisked away from the city.
During Rhaenyra’s half-year rule, Morgul lived in the Dragonpit with Dreamfyre, Tyraxes, Shrykos, and Seasmoke (before fleeing the city with his ridder, Ser Addam Velaryon). Rhaenyra’s relationships with the city residents deteriorated to the point of riots over time.
During one of these riots, a one-handed prophet known as the Shepherd began ranting against the dragons and convinced a mob of Kingslanders to march to the Dragonpit and kill them all.
Despite being shackled by thick chains, Morghul slew a large number of people with his fire. A gigantic warrior in heavy armor known as the “Burning Knight” is credited for killing Morghul. As the dragon drenched him in fire, he thrusted his spear into Morghul’s eye. Morghul died without ever being ridden.