Napoleon had a tremendous impact on many western nations long after his defeat. The most notable and positive example in my opinion is the base of the modern civil law system still in effect today in many of the conquered countries. The same codes based on the Napoleonic code were also exported to the colonies of those countries and many others which then retained it after their independence. See https://en.wikipedia.org/wiki/Napoleonic_Code. And IMHO the civil law is a much better legal system than the common law used in most of the US, the UK and Australia among others. This goes to show that it's never binary and even the worst tyrants and dictators also sometimes achieve good positive things. This is probably valid for all of them.