Contrary to appearances, these folks have very much in common. They all were strong advocates of a Manichaean light vs. darkness, us vs. them world view, and they all routinely performed the ritual which I call "disciplinarian populism."
Disciplinarian populism is a public ritual in which an authority figure publicly denounces and destroys an effigy of the "enemy of the people" usually represented by some unpopular minority figure or an outcast. The purpose of this ritual is to (i) express the power and authority relations in the most vivid and dramatic form, and (ii) allow the spectators to vicariously participate in this spectacle on the "winning" (i.e. the authority) side.
This hierophanic ritual literally embodies the power of the authority in the body of the condemned, as aptly captured by Franz Kafka in "The Penal Colony" http://www.mala.bc.ca/~johnstoi/kafka/inthepenalcolony.htm (and also by Orwell, cf. "a minute of hate"). The object of this ritual is to assert the power of the unquestioned authority that performs the rituals, but also gives the subjects an illusion of exerting that power themselves, only if vicariously.
Disciplinarian populist rituals are popular because of the cognitive setup of human mind. People need to cognitively establish order and meaning in the world to be able to function. They do it in two different yet complementing ways: (i) by establishing general core principles that define "essences" of classes of things and (ii) by drawing boundaries that separate members of one class from those of another. Although those two way usually work in tandem, different people often rely more on one or the other.
People's brains function differently - some have much less tolerance for ambiguity and complexity than the other. Those who have less tolerance for ambiguity and complexity, often rely on social norms and conventions to establish order and meaning by reducing that ambiguity and complexity. They tend to rely more on drawing clearly demarcated boundaries rather than essential principles that define objects on these two sides of the boundary. Essential principles add complexity and ambiguity that require additional interpretation - which genuinely scares these folks.
These folks have a natural tendency to gravitate toward racist, sexist, chauvinistic, law-and-order, homophobic, fundamentalist and jingoist ideologies, religions, and world views - because such views offer them the simplicity and the peace of mind that they need to function. In all likelihood the brains of these folks cannot function properly when their "circuits are overloaded" and they need external artifices (fundamentalist, law -and-order ideologies) to take off some of that pressure.
The fear of complexity and ambiguity grows particularly strong in times of social change, when conventional boundaries are being loosened or disappear altogether. Times like that genuinely frighten not only the hard core ambiguity anxiety cases, but also people who normally have some tolerance for ambiguity. But when social change is far reaching, e.g. revolutions, new technologies, profound changes in ethics and life styles, and "all that is solid melts into the air" - that creates the amount of ambiguity that is more than most people can handle.
In times of "vanishing boundaries," external artifices to re-establish boundaries, and thus order and meaning are in high demand. This is why fundamentalist religions and ideologies are on the rise in those periods. Fundamentalism may "clarify" things up in the mind of the followers - but that is not enough to re-establish order in society. That order requires an authority figure and power relations that are clearly recognizable by all (or most) subjects. Fundamentalism alone, that typically relies on some imaginary figure of a "supreme being", cannot do the trick, because it does not idetfy a flesh and blood individual as the source of authority and power..
Disciplinarian populism, however, does the trick of establishing social order based on a particular authority and power relations for two reasons. First, it is a ritual that uses hierophanic representations. These are representation whose very physical form embodies the relationship it signifies. In Kafka's story "The Penal Colony" the law was literally written with mechanical needles on the flesh of the condemned men. In medieval torture shows, the power of the rules literally torn the bodies of the condemned men into pieces for everyone to see. The modern disciplinarian populist shows may not be as gory, but they are nonetheless spectacle in which the power of the authority annihilates the physical existence of the condemned.
The second reason is that the population over which the authority is to be exercised is offered a symbolic stake in the authority. The authority is question does not pick its victims at random, but carefully selects those that are popularly feared, scorned or despised. They are the "enemies of the people," so to speak. In so doing, the authority figure re-affirms the "old" boundaries that separated "outcasts" from the "rest of the people" and brings in that old distinction into the service of new social order.
This is why Hitler who prided himself by propelling Germany into hypermodernity by building the autobahn, the Wolfsburg auto plant (the home of the WV "bug") and super modern Luftwaffe, Kriegsmarine, and Panzer division - relied so heavily on the most backward and old racial prejudices. The new authority needed to legitimate itself by evoking the ancient boundaries and class distinctions that defined social order in the past. As the Bearded One said: "The tradition of all the dead generation weighs like a nightmare on the brain of the living. And just when they seem engaged in revolutionizing themselves and things, in creating something that has never existed, precisely in such periods of revolutionary crisis they anxiously conjure up the spirits of the past to their service and borrow from them the names, battle cries and costumes in order to prevent the new scene in this time-honored disguise and this borrowed language" (_The Eighteenth Brumaire of Louis Bonaparte_).
What is more, the spectacle itself is carried out with maximum publicity, so the crowds can vicariously join in the executioner and throw insults at the condemned. Sometimes, the crowd is even allowed to participate more directly, as it was the case of pogroms or lynching - but such events are usually very carefully contained by the authorities, so they do not spill over and create a chaos. An out of control pogrom or lynching would turn into chaos and defeat the very purpose for which the spectacle was staged - i.e. creating order. That is why the Staat Pogrom Nacht (aka Kristall Nacht) was only a one time shot - after that, the Gestapo and SS took over. An that is precisely why Bush and Company do not want mobs attacking Arab targets in the US - that function is to be performed by Ashcroft Brigades and the Department of Homeland Security.
Figures like Stalin, Mao, Pol Pot, Hitler, or Bush arise in the times of increased ambiguity, uncertainly, and complexity triggered by political or technological events. They sense popular anxieties, and despite different cultural or ideological favor, they offer an essentially the same recipe to those anxieties - disciplinarian populism, rituals in which authority figures re-establish order by the acts of public destruction of "enemies of the people."
That explains the wide spread popularity of people like Stalin, Hitler, or more recently Sharon or Bush. People may dislike these men as individuals, but they ar even more afraid of the complexities and uncertainties that surround them. They are like children lost in woods happy to see their stern father who may punish them from straying for the course but at least takes out of the woods, back home.
In my opinion, this is perhaps one of the most scary and despicable aspects of human nature.
Wojtek