Pirate Captain

The title of Captain can refer to either a Captain of a pirate crew, or a rank in the Marines (note however, that this is meanly a coincidence in the English translation, as Japanese words for the two are not the same).

Pirate Captains
Pirate Captains are the ones who are at the very head of a Pirate crew. Pirating captains also tend to be the mightiest members of their crew, and most of them tend to exploit their strength even over their own subordinates to ensure loyalty; though not necessarily, as anyone can attain the rank of captaincy out of pure leadership or even as a founding member. All major decisions are made by them.

List Of Pirate Captains

 * Gol D. Roger
 * Monkey D. Luffy
 * Red-Haired Shanks
 * Buggy the Clown
 * Kuro
 * Don Krieg
 * Arlong
 * Whitebeard
 * Blackbeard
 * Macro
 * Bellamy
 * Montblanc Cricket
 * Foxy the Silver Fox
 * Mikazuki
 * Yorki
 * Lola
 * Capone Gang Bege
 * Jewelry Bonney
 * Eustass Captain Kid
 * Scratchmen Apoo
 * Basil Hawkins
 * Urouge
 * X. Drake
 * Trafalgar Law
 * Boa Hancock

Former Pirate Captains

 * Alvida (was Captain of the Alvida Pirates, now in Buggy Pirates)
 * Jango (was Captain of the Black Cat Pirates in Kuro's absence, now in Marines)
 * Wapol (became Captain while in exile due to the Blackbeard Pirates)
 * Fanged Toad Pirates Captain (now in Foxy Pirates)
 * Brook (was Captain of the Rumbar Pirates, now in Straw Hat Pirates)
 * Jean Bart (was Captain of an unknown crew, now in Heart Pirates)

Marine Captains
A Marine Captain (大佐) is a rank junior to that of a Commodore. It is second most seen rank in One Piece to date, having 8 representatives and being second only to that of Vice Admiral in terms of appearance. The number of seen captains MAY have surpassed the number of seen vice admirals, during the Enies Lobby assault on the Bridge of Hesitation, where no one below the rank of captain was to attack, we have not seen many of them more then once and only from from afar, except three (Sharingu, Shuu, Very Good) however, these were never specifically referred to as "captains", until being dubbed as such by Oda in the SBS of volume 47.

Trivia
Any naval officer below the rank of captain who commands a ship, is addressed as "captain" while aboard that ship, by naval custom. The ship's captain also may be referred to as the Skipper. A naval officer with the rank of captain traveling aboard a vessel he does not command is either never referred to by rank, or in some navies, is addressed as Commodore to avoid confusion with the ship's actual commander.

Current

 * Hina
 * Nezumi
 * T-Bone
 * Very Good
 * Sharingu
 * Shuu

Former

 * Smoker-promoted to Commodore
 * Morgan-discharged from the Marines

Commanding officers
Another position in the marines that is translated as captain, but different from the Taisa (大佐) rank is the Taichō (隊長) title, meaning captain or commanding officer. The marines that have this title are not the type of captain that's listed as a marine rank.
 * Attachan
 * Sentoumaru