Gerold Hightower
The White Bull: Lord Commander of the Kingsguard under Aerys II — brave, dutiful, entirely uncorrupt, and standing in the room for every single thing that king ever did.
A soul born at Oldtown.
The fuller tale
Their story
The White Bull is the hardest case the order has ever produced, and the reason is that there is nothing wrong with him. He was brave past any reasonable measure — he went out after the Kingswood Brotherhood himself, and he took a wound doing it that would have retired a lesser man. He was incorruptible; not one of the many people who tried to buy a Kingsguard in that reign ever seems to have thought it worth approaching him. He was a Hightower of Oldtown, which is to say he wanted for nothing and could not be bought with anything.
And he stood in the throne room while Rickard Stark cooked alive inside his own armour, and Brandon Stark strangled himself trying to reach a sword, and he did nothing, and he permitted nothing to be done. Not out of fear. Out of a reading of his vow: a Kingsguard defends the king, obeys the king, and keeps the king's secrets. He does not judge him. There is no clause about the king's victims because nobody drafting the vow ever imagined it would be needed.
Everything bitter in Jaime Lannister's worldview comes from having been seventeen years old and standing in that room next to him. The boy asked the Lord Commander what a Kingsguard was supposed to do when the king was the danger, and got an answer that was correct and useless in the same breath.
How it ends for them
Fell at a tower in the Dornish marches, before the story — before this story begins.
He died at the tower in the Dornish marches alongside Arthur Dayne and Oswell Whent, still guarding whatever he had been ordered to guard, obeying an order given by a prince who was already dead.
There is a consistency to him that is almost admirable and entirely terrible. He was the same man at the end that he had been in the throne room: a knight who had decided, once, what his vow meant, and never revisited the question again no matter what the answer cost anyone else.