Troy Tyrell was the son of Baelor Tyrell, and heir to Highgarden. He was hanged in King's Landing after the War of the Ascent of the Lion.
Troy Tyrell was raised at Highgarden in the Reach and groomed to assume the Lord Paramouncy, while his twin brother Olyvar Tyrell was encouraged to join the Citadel. He was rumored to be in an incestual relationship with his younger sister Maude Tyrell. As children, Troy, Olyver, and Maude were close friends.
Troy marched with King Harys Baratheon to Oldtown when his sister was kidnapped and rumored to be held there. In a fit of rage, he grabbed Lord Gylen Hightower and shoved him against a wall, breaking Guest Right and causing Lord Hightower to demand that the King and his men leave his city.
Once they heard that the captial was sacked, the King's army marched to Highgarden to muster the Tyrell forces and take back the throne. Along the way, Ser Thaddius Lannister of the Kingsguard betrayed the King and took Troy hostage, along with his younger siblings Benjen Tyrell and Mellara Tyrell. On the way to King's Landing, Thaddius forced Troy and Benjen to battle to the death, and Troy was victorious, killing Benjen and decapitating him. Ser Thaddius forced Troy to carry his brother's head back to the capital on his lap.
After the war's conclusion, Troy was hanged with his father by the King's Justice.
Baelor Tyrell, father (deceased)
Olyvar Tyrell, brother
Maude Tyrell, sister (deceased)
Benjen Tyrell, brother (deceased)
Meredyth Tyrell, sister
Mellara Tyrell, sister (deceased)