For Imperial Russia:

Peter the Great Era:
General Sheremetyev
General Gordon- some crazy Scot who served under Peter the Great and his father Alexius, real interesting person
Prince Alexander Menshikov


Late Catherine-Napoleonic times
Alexander Suvorov
Mikhail Kutuzov
Barclay DeTolly
Georgii Bagration


As for Austria, do not forget Mach.