The Shichibukai (Literally meaning "Seven Military Seas"), the full title being Oka Shichibukai (Literally meaning "Royal Seven Military Seas"), are seven powerful and notorious pirates who have allied themselves with the World Government.
The Shichibukai is an organization of seven pirates turned privateers in the service of the World Government. Although they work for the World Government, the Shichibukai do not care about or respect the Government (excluding Bartholomew Kuma, who was modified into their puppet) or even other Shichibukai, and are often considered by the Marines to be no different from any other pirate. On the other hand, they are known as "government dogs" and are despised by other pirates, but are still feared and respected for their infamous reputation and strength before, and even after they become Shichibukai.