No more half measures, Walder

Real hero of entire series was Mirri Maz Duur. She not only got some manner of revenge for her slaughtered and enslaved people, but she also saved most likely millions of people across entire Essos and Westeros by offing both Drogo and his unborn son (and it have solid ground to count since prophecies are quite often real in that world). Pity she didn't also killed Daenerys, that would prevent yet another series of conquests and massacres and living WMD usage.