Grand Admiral of the Imperial Starfleet

Spock

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 - Mirror Universe short story: "The Greater Good"; TOS - Mirror Universe novel: The Sorrows of Empire)

Mirror universe

• unnamed Grand Admiral (circa 2264)
• Grand Admiral Garth of Izar (until 2268)
• Grand Admiral Matthew Decker (2268–2277)
• Grand Admiral Spock (2277)
• Grand Admiral Zhao Sheng (2277)

Alternate mirror universe

• Grand Admiral Typhuss James Halliwell (2155-2209)
• unnamed Grand Admiral (circa 2264)
• Grand Admiral Garth of Izar (until 2268)
• Grand Admiral Matthew Decker (2268–2277)
• Grand Admiral Zhao Sheng (2277)
• Grand Admiral Spock (2277)
• Grand Admiral Typhuss James Halliwell (2384-present)

Alternate mirror universe (alternate timeline)

• Grand Admiral Typhuss James Halliwell (2378-present)