Bumping with a couple more.
1. Napoleon Bonaparte I: Our very own Napoleon has to take this list, as a general at the time, there were few men who could be equal. We speak in awe of his victories at battles such as Austerlitz, and his fine campaigning where he won battle after battle despite eventually losing the war when the Coalition had him on the run in France.
2. Arthur Wellesley: The Duke of Wellington is well remembered for his defeat of Napoleon at Waterloo, but it's for his earlier achievements that I bring him into this. His siege of Gawilghur (Spelling?) in India is no mean feat, as well as the battle of Assaye, which he always used to say was his toughest battle when people would ask him of it. His campaign through Portugal, Spain and eventually France is another example of his genius, managing to beat every Marshal Napoleon sent against him, even ousting the false King Joseph Bonaparte from Spain. And when he was finally matched against Napoleon, it was the good old Duke who bested him.
3. Trajan: The Roman Emperor who brought the Empire to its greatest extent upon his death in 117. He conducted a successful campaign against the Dacian kingdom, who were renowned for their savage fighting skills, having beaten Rome in a previous war and wiping out an entire legion. His subsequent invasion of Parthia was incredibly successful as far as Parthian campaigns go. He annexed Armenia as a Roman province, deposing the Parthian proclaimed king of the region and accepting the submission of multiple tribes in the area. He then began a conquest of Mesopotamia, taking the great cities of Babylon, Seleucia and finally, the Parthian capital of Ctesiphon itself. He even managed to depose the Parthian king, and wipe out a surge of resistance from the nephew of said king. It is a shame he wasn't a younger man, or he could have continued on with his conquest.
4. Alexander Suvorov: This Russian commander is one of few men who is famed for never losing a battle in his entire career. His tactics often employed decisive charges with the bayonet, preferring not to rely on musketry too much. And while my history on Suvorov is sadly lacking, even I can realise his genius. Once again, if he had been but a little younger, perhaps Napoleon wouldn't have had such success as he experienced.