The worst Kingsguard members

[Lord Varys]

2 hours ago, Daemon of the Blacks said:

Cole is a pretty serious contender. 

The reasons you give seem to be also the reasons why Cole is loathed as one of the worst Kingsguards in history. Even those people who believe Aegon II's coronation was the right thing to do - and some people certainly believe that this was the case - would acknowledge that a Kingsguard shouldn't have been the one to do it, especially not a Lord Commander. Nor should such a person be a driving force behind the entire 'kingmaking business'.

Lords and courtiers outside the KG, sure, but not the KG. Especially not if doing that kind of thing goes directly against the decrees and wishes of the previous king. Crowning Aegon II was a fundamental betrayal of the trust of Viserys I. And since Aegon II was king until Cole crowned there is really no excuse for him there.

2 hours ago, Daemon of the Blacks said:

Part of the reason is sheer scale. Men like Meryn Trant or the Peake cronies are scumbags who might have caused dozens of death, and Lucamore had some kids but Cole's actions caused the deaths of thousands of people and crippled his dynasty. 

Causing the Dance is certainly also something Cole can be blamed for. As Kingmaker he made the king who started the war, but he was also the driving force behind the escalation of hostilities and violence.

But I'd say that there are wars the KG can start which are justified, no matter how many innocents die. The duty of the KG is to defend and obey the king, not to restore or keep the peace and defend the weak and innocent from the rule of their betters. Selmy helping Dany to retake her father's throne is an honorable thing to do for a KG, Marbrand and Darklyn and Cargyll defending Rhaenyra and her children against Aegon II usurpation is admirable, too, as it would it have been if some of Aenys' KG had joined Aegon the Uncrowned in his attempt to overthrow Maegor.