Terrence Toyne

Terrence Toyne is an unseen character in Game of Thrones. He is long dead before the start of the series, and thus is not expected to appear. Terrence Toyne was a renowned knight and member of the Kingsguard.

Season 4
Terrence Toyne is mentioned within the entry of Aemon the Dragonknight in the Book of Brothers. It is said that he was defeated by the Targaryen prince in the final joust in a tourney at Riverrun.

In the Books
In the books, Ser Terrence Toyne was once found abed was found abed with one of King Aegon the Unworthy's mistresses. Even though they proclaimed love, Aegon had them executed. Toyne was dismembered piece by piece, while the mistress was forced to watch before meeting her own death. Ser Terrence's brothers attempted to avenge him by killing King Aegon, but were stopped by Prince Aemon the Dragonknight who died defending him instead. They paid for their treason with their lives and in turn this event was key in the downfall of House Toyne, which in a few generations devolved into a family of rogues and robber knights. Simon Toyne, the leader of the Kingswood Brotherhood was the last of his line.