Admiral

Admiral (大将, taishō) is a title of admiral signified senior command rank in the Marines. Admirals, also known generally as flag officers, were typically responsible for a high level military command at battle group or fleet level, and/or for administrative and political duties relating to Marine operations.

In One Piece, Admirals are shown as being the second most powerful rank behind the Fleet Admiral.

Pirate Admiral
The only known pirate Admiral is Don Krieg who commanded 50 flag ships with two of his commanders Pearl and Gin

Marine Admiral
There are only three Marines with the title of Admiral in the Marines. They are known by their aliases, "Blue Pheasant" (Aokiji), "Red Dog" (Akainu), and "Yellow Monkey" (Kizaru). These are similar to characters in the fairy tale Momotaro. Theese three admirals and the Fleet Admiral are the only Marines within the World Government who are capable of issuing Buster Calls.

Only one previous Admiral has been shown since One Piece began and that is Sengoku; this was seen during Episode 277.

List of Admirals
Only 3 Admirals are seen in One Piece serving in the Marines under Sengoku.
 * Aokiji
 * Akainu
 * Kizaru