Oswell Whent
A knight of the Kingsguard under Aerys II, of the house that held Harrenhal — Rhaegar's man, and the third of the three white cloaks who were not at the Trident.
A soul born at Harrenhal.
The fuller tale
Their story
The Whents held Harrenhal, that vast ruined bat-haunted heap on the Gods Eye, and it was a Whent tourney — the great tourney at Harrenhal, thrown for reasons nobody has ever satisfactorily explained — that set the whole rebellion in motion. Ser Oswell was of that house, wore its black bat on his helm, and was by every account a dry, sardonic man who was better company than most of his brothers.
He was Rhaegar's, in the way that a few of the white cloaks quietly were. Where the prince went, he went; what the prince was doing, he was near. That is nearly all the record says of him, and the little it says is arranged very carefully around a silence.
He is the third man at the tower. He is also, if you follow the tourney and the prince and the year, standing somewhere near the centre of every event that brought the Targaryen dynasty down — never as the man deciding anything, always as the man holding the door.
How it ends for them
Fell at a tower in the Dornish marches, before the story — before this story begins.
He fell at the tower in the Dornish marches with Ser Gerold and Ser Arthur, three against seven, and took two northmen with him.
His house did not long outlive him. Harrenhal is cursed, and everyone who has ever held it has learned so; the Whents were simply the ones whose turn it happened to be.