Barristan Selmy

Barristan Selmy, born around 236 AC, slew the pretender Maelys the Monstrous in single combat during the War of the Ninepenny Kings at only twenty-two or twenty-three, a feat that ended the war outright and earned him a Kingsguard cloak from Lord Commander Ser Gerold Hightower in King Jaehaerys II's final years on the throne. He went on to serve with a reputation for valor that outlasted three more kings, riding at the Trident where Rhaegar Targaryen died and taking wounds there fighting, by his own reckoning, for the losing and the wronger side, a weight he has never stopped carrying.

Robert Baratheon, who respected little from the dynasty he'd overthrown, kept Barristan on as Lord Commander of his own Kingsguard rather than execute or exile him — one of the very few Targaryen loyalists Robert ever forgave — and Selmy repaid it with fifteen more years of honest service to a king who mostly ignored his counsel.

Days after Robert's death, Joffrey and Cersei stripped Barristan of his cloak in open court on grounds of age alone, a public humiliation the old knight had done nothing on the page to earn. Stunned and, by his own account, briefly suicidal, he instead crossed the narrow sea under a false name, Arstan Whitebeard, to find the one Targaryen he judged still worth serving.

He revealed himself to Daenerys Targaryen in Meereen, becoming one of her most trusted protectors, and after her disappearance on Drogon's back, one of the small handful of people left holding the city together in her name — the published chronicle leaves him there, an old knight once discarded now effectively governing a city he never asked to rule.