I'm talking about moments that if somebody told you before it occured that this would happen, you would write it off as ASB, but turned out to be quite the opposite. Here's what I can up with...
Adolf Hitler as Dictator of Germany - Its hard to believe that a glorifed criminal not only took the Chancelorry/Presidency of Germany, but unleashed hell on all of Europe and caused a Second World War. From a failed artist in Vienna to a man who was set in motion to conquer the World, I doubt many people saw that coming. In fact, even up to the early 30s, people looked at "That Austrian Corporal" as a joke of a politician considering all he's been through previously. Well, once he established his position as Führer, Awful Adolf was the one who was laughing. Well, at least briefly as his 1000 Year Reich only lasted a mere 12.
The Holocaust - As an extention of Hitler's reign of terror, 11 to 17 million people suffered his wrath. Mostly Jews, but also Gypsies, Slavs, homosexuals, mentally and physically handicapped, political opponents, and many others the Nazis deemed "undesirable." While Hitler's racism/anti-semitism was well-known at the time, few people knew to what extent. The first reports of a mass murder happening in Europe was dismissed as propaganda, since the idea of a genocide taking place in a culture advanced as there's was hard to believe. At the end of the war, the public found out about Hitler and The Nazis evil intentions and couldn't believe the carnage thats been inflicted upon those victims. Even shortly thereafter, it was hard to process what just happened, but it was very real especially to those who have seen it first hand...
Ayattolah Khomeni Becoming The Supreme Leader of Iran - While a devouting religious 80 year old Muslim overthrowing the once powerful Persian Empire is looked at as laughable, the fact that he did so, and without any signs of that happening(I know it was building up, but that was only thanks to hindsight) makes it all the more impressive.
On a lighter note....
Abraham Lincoln Becoming President - A self-educated log cabin born simpleton who had minimal military experience to become not only President of the most powerful Nation in the World, but one of, if not the greatest President of all time is something to behold. Honest Abe is also the most biographed person(or at least one of) in history.
Anything you can think of?