|Died||In 130 AC, King's Landing|
During the storming of the Dragonpit in 130 AC, Prince Joffrey Velaryon attempted to save the dragons in the Dragonpit from the crazed mob, by flying there from the Red Keep on his mother's dragon, Syrax. Queen Rhaenyra Targaryen sent the Seven Who Rode, including Ser Willam, to rescue her son and heir. Willam and the other six knights faced many perils as they fought their way across King's Landing, while the city burned in riot.
Unfortunately, Prince Joffrey fell from Syrax and died from the impact, and the mob began tearing apart his remains. While trying to recover Joffrey's body, three of the Seven died fighting the mob. Willam Royce was killed when a man leaped down from a rooftop to land on his back. Willam's Valyrian steel sword Lamentation was torn from his hand and carried off, never to be found again.
- Fire & Blood, The Dying of the Dragons - Rhaenyra Overthrown.