Pirate Captain

Luffy wasn't the first pirate of the series but it's the one that made this anime famous

The title of Captain is the title given to the person in charge of a ship at sea, either pirate, marine, or civilian.

The rank of a marine officer who commands a ship should not be necessary Captain (Taisa), it may be higher (up to Fleet Admiral), or, on small ships, lower. Any officer below the rank of Taisa 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.

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 (Deceased; Roger Pirates)
 * Monkey D. Luffy (Straw Hat Pirates)
 * Alvida (Formerly Alvida Pirates, Second captain of the Buggy Pirates)
 * Shanks (Former apprentice of the Roger Pirates; Yonkou; Red-Haired Pirate Crew)
 * Buggy the Clown (Former apprentice of the Roger Pirates; Buggy Pirates)
 * Kuro (Black Cat Pirates before and after disguising as Kaya's butler 'Kurahadol')
 * Don Krieg (Admiral of the Don Krieg's Pirate Armada)
 * Arlong (Incarcerated; Former member of the Sunny Pirates; Arlong Pirates)
 * Edward Newgate (Deceased; Yonkou; Whitebeard Pirates)
 * Marshall D. Teach (Former member of the Whitebeard Pirates; Blackbeard Pirates)
 * Macro (Former member of the Sunny Pirates; Macro Fishman Pirates)
 * Puppuu (Piggy Pirates)
 * Bellamy (Bellamy Pirates)
 * Montblanc Cricket (Former captain of an unnamed crew; Leader of the Saruyama Alliance)
 * Masira (Captain of one portion of the Saruyama Alliance)
 * Shoujou (Captain of one portion of the Saruyama Alliance)
 * Foxy (Foxy Pirates)
 * Mikazuki (Big Helmet Pirates)
 * Yorki (Deceased; First captain of the Rumbar Pirates)
 * Lola (Rolling Pirates)
 * Capone Bege (Firetank Pirates)
 * Jewelry Bonney (Bonney Pirates)
 * Eustass Kid (Kid Pirates)
 * Scratchmen Apoo (On Air Pirates)
 * Basil Hawkins (Hawkins Pirates)
 * Urouge (Fallen Monk Pirates)
 * X. Drake (Former Marine Rear Admiral; Drake Pirates)
 * Trafalgar Law (Heart Pirates)
 * Boa Hancock (Former slave; Shichibukai and empress of Amazon Lily; Kuja Pirates)
 * Fisher Tiger (Deceased; First captain of the Sunny Pirates)
 * Largo (Amigo Pirates)

Former Pirate Captains

 * Jango (Second captain of the Black Cat Pirates; Currently a member of the Marines)
 * Jinbei (Second captain of the Sunny Pirates; Renounced Shichibukai)
 * Wapol (Wapol Pirates; Former king of Drum Kingdom (now called 'Sakura Kingdom'); Currently a CEO of his own toy company)
 * Kiba (Fanged Toad Pirates; Currently a member of the Foxy Pirates)
 * Brook (Second captain of the Rumbar Pirates; Currently a member of the Straw Hat Pirates)
 * Gecko Moria (Fate unknown; Unnamed crew was massacred (implied to be by Kaidou of the Yonkou); Formerly a member of the Shichibukai)
 * Dias (Acumate Pirates; Former slave; Currently in custody of the Marines)
 * Jean Bart (Unnamed crew; Currently a member of the Heart Pirates)
 * Portgas D. Ace (Deceased; Spade Pirates; Currently Second-Division Commander of the Whitebeard Pirates)

Trivia

 * Supernova, Eustass Kid has a nickname of "Captain".
 * In real life, captains of pirate crews were often elected to their posts by a ships crew. Even if they owned the ship, if the captain fell out of favor with her crew, another could be elected without notice. Sometimes, bad captains were even murdered.