Same word as overthrower:

agitator, anarchist, antagonist, apostate, demagogue, deserter, disectarian, dissenter, experientialist, experimenter, frondeur, guerrilla, heretic, iconoclast, independent, individualist, innovator, insurgent, insurrectionary, malcontent, mutineer, nihilist, nonconformist, opponent, overthrower, recreant, renegade, resistance, revolter, revolutionary, revolutionist, rioter, schismatic, secessionist, seditionist, separatist, subverter, traitor, turncoat