It's almost clique in that 'edgy' kind of way, but I think in terms of bare leadership, Adolf Hitler was a pretty strong figure. Though this is quite an ignorant position admittedly, I only know of the context of Germany itself around Hitlers rise, and not of his personal acts to structure and use Germany.

A figure I think is worth some mention is Lycurgus of the Spartans, he established the government and social structure of Sparta that made it such a powerhouse for a long time. Even when the rest of the ancient Greeks were facing political reprisal and collapse, Sparta's system remained mostly unscathed and their dedication to military power as well as the structure to obtain such, all starting with Lycurgus, was quite amazing to learn about.