The Warlords of the Sea (七武海, Shichibukai), are powerful and well-known
pirates who have allied themselves with the World Government.
The Warlords of the Sea is an organization of pirates turned privateers in the service of the World Government. Although they work for the World Government, the Warlords do not care about or respect the Government (excluding Bartholomew Kuma, somewhat) or even other Warlords, and are often considered by the Navy 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 Warlords of the Sea.
The Warlords of the Sea seem to be a mixture of the more chaotic World Emperors and the more orderly Navy. The majority of the Warlords are composed of New World veterans; those who have met the World Emperors or even confronted them.
There is an enormous range in the bounties between the members due to differences in circumstances under which they were recruited, with Bartholomew Kuma, who has a former bounty of former 340,000,000 berries, Don Quixote Doflamingo, with 250,000,000 berries, and Blackbeard, with no former bounty at all. It should be noted that these are their former bounties, and doesn't represent the current threat they could achieve as active pirates. Jimbei, for example, after his resignation his bounty jumped to over 400,000,000 berries. Another example is Crocodile who was imprisoned in Level 6 of Impel Down, while Luffy with a bounty of 300,000,000 Berries at the time put him only at Level 5.
The terms that the Warlords of the Sea are on with each other is best described as very unstable. They have very little (if any) respect for each other and will for the most part not accept help from one another, apparently from a firm sense of pride. During the battle meeting for the Warlords where only two members are absent (Hancock and Jimbei), it is even stated that the very notion of them working together as a team is entirely unthinkable. However, Kuma and Doflamingo don't disregard the notion of teaming up with another Warlord: Kuma offered Gecko Moria help defeating the Straw Hats and Doflamingo offered Crocodile a chance to team up. Both offers were refused due to pride.
During Boa Hancock's visit at Impel Down's Level Six, Jimbei stated that he didn't know much about her, possibly suggesting that only some of the Warlords are familiar with each other or even have personally met all the other members. Despite this, all of the Warlords of the Sea (including former) fought at the war between the Whitebeard Pirates and the Navy.
Most of the Warlords have a jaded attitude of the world, as their vast amounts of experience have disillusioned them. Crocodile and Moria both disregard Luffy's arrogant behavior, saying that he is too inexperienced to know what the world is truly like; Dracule Mihawk behaved in a similar fashion in his duel with Roronoa Zolo, though he hopes that he'll be successful. Doflamingo believes that there is no true justice in the world, and that both the Navy and Pirates are foolish if they think that they are upholding it. Hancock, through her horrid experience as a slave, considers all men of the world to be scum, outside of Monkey D. Luffy, with whom she is in love (and anyone who Luffy is on good terms with); Silvers Rayleigh, who is her "benefactor"; and Fisher Tiger, who was responsible for freeing her from slavery.