Shichibukai
The Shichibukai is an organization of seven privateers that are in the service of the World Government. These seven individuals are former pirates that hunt active pirates, though they apparently share a percentage of their income collected from this bounty hunting with the World Government, and possibly act as informants or intermediaries with active pirates. In exchange for these services, the Shichibukai are pardoned for their former actions and any existing boutnies are rescinded.
The Shichibukai are one of the Three Great Powers that help maintain the balance of the Grand Line, though they seem to be a mixture of the more chaotic Yonko and the more orderly Marines. They do not offer open opposition to the rule of the World Government, but are not guaranteed to follow its orders either. Judging by the those instances where the Shichibukai have interacted with one of the other Powers, they seem to be on closer terms with the Yonko than the Marines, whom several of the Shichibukai appear to hold in open contempt. This is not surprising as they are former pirates themselves.
The Shichibukai are apparently granted a great deal of autonomy in how they operate from what has been shown to date. Crocodile seems to have been unsupervised for an extremely long period of time and several high-ranking Marines expressed surprise that several of the Shichibukai actually bothered to show up when summoned for a meeting. Presumably the World Government tolerates these actions from the Shichibukai because even a reticient Shichibukai is still better than an active pirate of that strength.
Because of their deal with the World Government, the Shichibukai are considered "Government Dogs" by other pirates. At the same time, they are also feared by them because all of the Shichibukai are insanely strong. The Shichibukai named to date are:
- Dracule Mihawk
- Jinbei
- Sir Crocodile
- Donquixote Doflamingo
- Bartholomew Bear
After the defeat of Sir Crocodile by Luffy, the Gorousei order a search for a replacement. This was due to the fear that the hole left by Crocodile could disrupt the balance of the Three Powers. An emissary of the Blackbeard Pirate Crew offered their captain as a potential candidate, but was initially rebuffed by Sengoku as lacking the necessary name recognition for the role. However, Doflamingo spoke out on his behalf and insisted that they be given a chance to prove Blackbeard worthy of the role.
To date, he has not yet been confirmed as Crocodile's successor.