|Born||In 211–219 AC|
|Died||In 233 AC, at Starpike|
|Book(s)||The World of Ice & Fire (mentioned)|
Tywald was the eldest son of Gerold the Golden, Lord of Casterly Rock, and Lady Rohanne Webber, his second wife. In his youth, Tywald was betrothed to Ellyn Reyne and was a squire to her father, Lord Robert Reyne of Castamere.
During the Peake Uprising in 233 AC, Tywald fought on the side of King Maekar I Targaryen, but he was mortally wounded by a spear at Starpike. Prince Aegon Targaryen knighted the squire, while Tywald laid dying in his twin brother Tion's arms. According to a semi-canon source, Tywald asked his brother to "take care of Lady Ellyn" with his final words. This later led Lord Gerold to agree to a betrothal between Tion and Ellyn.