hmmm... i think King Leonidas being Mandalore of the mandalorians would be pretty cool
Genghis Khan as Mandalore of the neo crusaders.
Karl Donitz as an Admiral of the Imperial Navy.
Horatio Nelson as a Grand Admiral of the Imperial Navy <--- perhaps would be Thrawns equal and or rival?
Caesar as senator and general of the Republic <----- perhaps a very powerful political opponent of Palpatine during the rise of the empire. would be pretty cool to see these two duke it out in a civil war parallel to the Roman Civil war that caesar fought with Pompey for control of Rome
Robert E. Lee as a general of the Rebel Alliance.
Attila the hun as a deep core warlord would pretty entertaining to see xD