An institution from Westeros, the Kingsguard exists to... guard the king, and anyone close to him. They consists of seven knights who swear themselves to bachelorhood, celibacy and duty, serve for life, and wear pure white when on-duty. Members of the Kingsguard, by virtue of being members, are considered the de facto finest knights in the realm, and all of them are at least excellent fighters; whether they are Pillars of Moral Character is another question. Daenerys has gone to the effort of constituting a new Queensguard, which confers some legitimacy on her claim, but due to various circumstances it has never had more than one knight in it at a time.