The Grand Admiral of the Imperial Starfleet was the most senior flag officer of the Imperial Starfleet. The Grand Admiral served as a primary military advisor to the Emperor or Empress of the Terran Empire, and had operational control over the Imperial Starfleet. The position was also known as Commander-in-Chief of the Imperial Starfleet (C-in-C). (TOS novels: The Sorrows of Empire, The Greater Good)