Admiral (Starfleet)

From Memory Alpha, the free Star Trek reference.

Admiral insignia
Starfleet pin insignia, 2280s until early 23rd century
Starfleet sleeve insignia, 2280s
Starfleet, 2365-present
Terran Starfleet epaulet insignia (admiral and fleet admiral)

In Starfleet there are several grades of the rank admiral.

Starfleet admiral is a military rank, the equivalent of which is used by the service organizations of many civilizations. As a traditional naval grade, admirals command fleets of ships, as opposed to captains commanding single ships or units. Many rank systems, including that used by various incarnations of Starfleet, have been known to use several grades of the admiral rank, which include, in order from most senior: fleet admiral, admiral, vice admiral, rear admiral and rear admiral lower half (also known simply as commodore).

See the List of Starfleet admirals for Starfleet admirals of all grades.

"Full" Admirals

These admirals held the flag officer grade higher than a vice admiral and lower than a fleet admiral:

• Bullock (Starfleet Command)
• Owen Paris (Starfleet Communications)
• Strickler (Starfleet Headquarters)
• T'Lara
• Charles Whatley
• Black in the mirror universe (Terran Empire Starfleet)
• William T. Riker in an unknown, alternate future timeframe (Commanding officer, Starbase 247)

Flag officers, regardless of title or grade (possibly excepting commodores), could be referred to as "admiral", meaning that many admirals referred to in dialog or other references where they were not seen could possibly hold this specific grade.