9. Home To 400,000 Droids
The humanoid crew obviously would have been useless without the support of the huge masses of droids aboard, available for every imaginable use. Repairs, maintenance, communication; there was no form of robot the Empire couldn't find a way to enslave!
Who can forget the adorable Mouse droid? Resembling more of a toaster on wheels, these droids were for scientific research, medical assistance, domestic service, sanitation and interrogation.
Also noted in the technical companion book, having versatile droids meant the the Empire could cut down on cost. Probably not a bad idea in case anything should happen to your beloved super-destroyer...