The novel political regimes that we associate with Mussolini, Stalin, and Hitler fundamentally altered our sense of the political spectrum, even the range of human and historical possibilities. Defying expectations, each emerged in the wake of the First World War spearheaded by a new elite that claimed to offer a new vision in response to inadequacies in what had seemed the political mainstream so far. Each rejected liberal individualism and parliamentary democracy, and each featured unprecedented mobilization for grandiose projects. Indeed, each seemed to galvanize genuine enthusiasm for acting collectively, beyond immediate individual self-interest. At the same time, each engaged in coercion, violence, and sometimes terror or even systematic killing. Whereas the regimes of Hitler and Mussolini came crashing down in overt imperialism and war, the Soviet Communist regime survived the extremes of Stalinism only to unravel, with a whimper, two generations later.