Eddard "Ned" Stark
Eddard Stark, Lord of Winterfell and Warden of the North, becomes the Hand of the King to Robert after Jon Arryn's death. He discovers Cersei and Jaime's secret, and is executed by Joffrey for treason soon after.
King Robert: You heard The Hand. Go find the breast plate stretcher. Now!
Ned: The breast plate stretcher?
King Robert: How long before he figures it out.
Ned: Maybe you should have one invented.
Jaime: It must be strange for you, coming into this room. I was standing right here when it happened. He was very brave, your brother. Your father, too. They didn't deserve to die like that. Nobody deserves to die like that.
Ned: But you just stood here and watched.
Jaime: Five hundred men stood here and watched. All the great knights of the seven kingdoms. Do you think anyone said a word, lifted a finger? No, Lord Stark, 500 men and this room was silent as a crypt. Except for the screams, of course, and the Mad King laughing. And, later, when I watched the Mad King die, I remembered him laughing as your father burned. It felt like justice.