Who Were History's Great Leaders?

When I first saw your question I was curious to see where you were going. I have often said that some of the cruelest dictators have provent to be some of the most effective leaders, i.e. Hitler, Stalin, Napoleon, Alexander etc. These were people who were able to rebuild societies and brought them to great levels; however ultimately greed overcame their ideals and they eventually sucbed to their faults. I think that including Pasteur and Salk in this is a little bit of a stretch; yes, they led others in their field, but are not known as people who have brought societies to greatness (arguably of course). I think you may have asked a question with no true answer, as there is so much opinion that can influence the results; however, it is great to discuss these things as it makes us better for simply thinking about it.