Joachim Murat: Flamboyant cavalry commander under Napoleon. King of Naples in 1815.
Paul von Lettow-Vorbeck: German Commander during World War 1. Was only commander during the war never to lose a battle. During the 1960s, Charles Miller asked the nephew of a Schutztruppe officer, "I understand that von Lettow told Hitler to go fuck himself." The nephew responded, "That's right, except that I don't think he put it that politely." Badass 'nough said.
Theodore Roosevelt: Not even going to explain this one.
Genghis Khan: Established the worlds largest land empire. When asked about the destruction of the massive Khwarezm Empire. He said he was the punishment of god and if they had not committed great sins. He would not have to destroy them.
Ramses the second: Pharaoh of Egypt. Rebuilt Egyptian Empire. Created the first alliance with the Hittite. Meaning that others on here wouldn't even be here without him. Though while not a totally successful military leader. He is certainly the Pharaoh with the biggest legacy.
Fredrick the Great: King of Prussia during the seven years, Silesian, and Seven Years War. Without him there would be no strong Prussia to unite Germany. Under his leadership the Arts flourished. He was good friends with Voltaire.
Alexander the Great: Created an empire stretching from Greece to India and spreading Greek Ideas all across the known world. All in his 20's.
Themistocles: A skilled admiral who at the battles of Artemisium and Salamis stopped the Persian fleets from being able to supply their armies. Thus saving the whole western world and democracy.