Moffs and Grand Moffs
A rank that originated during The Clone Wars which combined civilian and military authority in one role. It was an emergency measure during a time of chaos that was need to coordinate both areas of authority. Moffs were thus either former High Admirals (who command Sector fleets) or Field Marshals who now gained civilian/judiciary powers in their Sector.
A Moff was in charge of a Sector, the largest unit of governance within the Old Republic. Grand Moffs were placed in charge of multiple sectors. These groupings were called Oversectors and the amount of territory (the number of Sectors) each one comprised could change as needed. Only where there had been an almost complete breakdown of government control in multiple Sectors would Oversectors be created and Grand Moffs be appointed.
Crucially, Grand Moffs are created via executive order of The President of the Senate and answer directly to his authority.