Boa Hancock

The Pirate Empress Boa Hancock (海賊　女帝　ボア・ハンコック) is the only female member of the Shichibukai and was first mentioned by one of the Risky Brothers while he was talking about Mermaids to Sanji and Brook. She is the Snake Princess (蛇姫) of Amazon Lily and rules over it with her two younger Gorgon sisters, Boa Marigold and Boa Sandersonia.

Appearance
Compared to the abnormal appearance of her sisters, Hancock is a slender, tall woman with long hair dressed in a one-piece outfit. This beautiful appearance is noted by many throughout the world: to one of the Risky Brothers, her beauty is second only to that of the mermaids, while Marguerite claims she is the most beautiful woman in the world. Like every Shichibukai member, she has an animal theme: snake.

On her back is supposedly two Gorgon eyes, but this seems to be a lie. While it is unknown what exactly is on her back(which is later revealed to be the slave mark of Tenryuubito), she is willing to kill, or turn to stone, anyone who sees it, to keep it a secret.

Personality
Whether I kick a kitten... Tear off your ears... Even slaughter innocent people... The world will never cease to forgive my actions! Why, you ask? Why it is because I am... Beautiful!!!

-Hancock's justifications for her actions.

Hancock is a selfish, pompous and spoiled person who is used to having her own way, although she does lie to the World Government about her agreement to wage war with Whitebeard simply to get them off her back temporarily. She is arrogant and cruel, justifying her actions with her apparently unmatched beauty and thinks that she can get away with anything because the world will forgive her. Her sister Sandersonia cheerfully calls her personality "Twisted". She has also proven that she will openly lie and her confidence leads her to never consider the consequences of her actions.

While a member of the Shichibukai, Hancock doesn't think much of the World Government and would rather keep her title but not go to war or perform certain duties if she had to, preferring to use her position to presumably nullify her former bounty and to protect her home from the government who sees all of the Kuja as pirates. She doesn't think twice about killing her so called Marine allies. She also apparently doesn't think much of the Kuja tribe either as she comments to Elder Nyon that she doesn't care if the island destroyed or not since everyone will forgive her because she is beautiful. However, it was revealed the reason for Hancock's lies and attitude towards life was that because of her past she didn't want to ever show weakness again to anyone, even if she has to decieve all of the other Kuja.

Because of her beauty and powers, she is used to seeing men and women whether young or old fall instantly in love with her. As a result, people forgive her when she acts cutely apologetic or reminds them of her beauty. However, as proven when Luffy comes along, she cannot bear the existence of someone completely immune to her powers.

Her oddest trait seen so far is that when she looks down on people, she leans backwards so she faces the ceiling (or the sky) above her, apparently "looking down on people so much she's looking up."

Friends
Hancock is on good terms with Luffy, who saved her and her sisters after Sandersonia nearly exposed her mark on her back. After hearing his opinion of the World Nobles, along with the fact that he went so far as to actually attack one, Hancock takes a liking to Luffy.

Marigold & Sandersonia
Hancock is close to her sisters because they went through a lot together as slaves. The three of them have a strong bound and support each others' actions.

Elder Nyon
Hancock takes the role of the ungrateful brat to Nyon, even though Nyon helped her and her sisters get back to Amazon Lily. Hancock likes to make sure that Nyon remembers she is a traitor to the Kuja, despite Nyon having treating them as though they were her own daughters.

Abilities and Powers
Ruling beside her sisters, Hancock has power over Amazon Lily and the rest of the Kuja women. As the Empress and Captain of the tribe, she is possibly the strongest Kuja warrior. Apart from her great beauty, Hancock has the ability to turn people into stone. This occurs when her hands form a heart shape, and beams are shot out of the shape. Anyone with "dirty thoughts" will be turned into stone as long as they do not have a means to block it out emotionally like with fear or pain.

She also can use the Haoushuku Haki, an ability of one in a million people can use. From the example shown by Luffy, it can be assumed that she can knock out a large number of individuals (with the exception of strong-willed people) with a massive burst of Haki. This perhaps adds as an additional reason why she is both adored and feared amongst the Kuja.

Weapon
She carries an extra large Snake Weapon with her, however she has yet to use it in battle.

Past
When Boa turned twelve, she and her sisters were captured by slavers and sold to the Tenryuubito. During her time as a slave, Boa was fed the Mero Mero no Mi to entertain her captors. The three suffered horrors beyond imagine until a man by the name of Fisher Tiger appeared and while his goal was simply the liberation of the Fishman slaves, he freed as many as he could without discrimination. Left with nowhere to go, the sisters were eventually rescued by Elder Nyon and brought home, but the Hoof of the Soaring Dragon, the symbol of the Tenryuubito was burned deep into their flesh. Boa chose to hide the mark and her Devil Fruit powers, claiming them to be punishment for slaying a gorgon. At some point later on, she opted to join the Shichibukai in order to protect her fellow Kuja.

Straw Hat Separation Arc
Hancock's first appearance is three days after Bartholomew Kuma had sent Monkey D. Luffy flying on her island (not to her knowledge). After sailing with her all-female crew, they met upon a Marine ship led by Vice Admiral Momonga, who told Hancock that the Shichibukai were being summoned to prepare for the upcoming war against Whitebeard, due to the execution of Portgas D. Ace a week from then. However, Hancock refused, stating that she would not obey the World Government, even though she fancied her Shichibukai position. When Momonga threatened to revoke Hancock's position if she didn't comply to the summoning, she came up with a make-believe story: The Marine crew would have turned into stone mysteriously.

She also demanded all the treasure on Momonga's ship (which the Marine rookies happily and absent-mindedly complied to), and justified her selfish actions by claiming herself to be "beautiful", which everyone present (save for Momonga) vehemently agreed with. Then, she preformed a special move that mysteriously turned the Marines to stone, save for Momonga, who had stabbed his own hand to avoid the effects of her attack. As her crew sailed away, Momonga remarked that he would wait for two days, and if she didn't follow him, the treaty with the Kuja would be null and void. She arrogantly told him to "Do as [he] pleased".

Upon returning to Amazon Lily, Hancock was greeted with plesantries though concerned that the warriors were not around, due to them chasing after a "monkey". She speaks with Elder Nyon (herself a former Kuja leader) about the danger that would befall Amazon Lily if she does not comply with the Government orders, but she remains arrogant and confident that both her power and beauty will allow her to get her way, throwing Nyon out of a window to prove she was right. When deciding to take a bath in privacy, she unexpectedly encounters Luffy, who falls down into her private area while looking for the person in charge, wanting to borrow a boat. He manages to see the symbols on her back and comments that he has seen them before. She attempted to petrify Luffy, but Luffy, being simple-minded, mistook the beam for a Noro Noro Beam (which Foxy used to slow Luffy down several times) and panicked. The beam did not have any effect on him though. Luffy attempted to run away, but ended up captured and thrown in the arena.

In the combat arena, Hancock shows no mercy to Luffy or anyone who tries to defend him, turning Marguerite, Sweet Pea and Aphelandra to stone for attempting to defend him after they admitted to bringing him to their country. At first she attempted to have Bacura execute Luffy, but he knocks it out with a single punch, and after she realizes that Luffy is not attracted to her in any way, and is in fact disgusted by her behavior, she nearly collapses and, out of desperation, sends her younger sisters to attack him in the arena ordering them to bring back his head. After Sandersonia attempted to shatter Marguerite, Luffy released a very high level of Haki, which caused some Kuja to faint, Hancock noted that Luffy has achieved the level of Haki that she herself has. After Luffy defeated Hancock's younger sisters, when Sandersonia's back is about to be revealed to the Kuja audience, Hancock ordered everyone to evacuate the stadium. The Snake Princess is then seen crying silently to herself.

After offering Luffy the choice between de-petrification for the Kuja Warriors or a boat home (expecting Luffy, as a man, to be selfish), Hancock is surprised to find that Luffy does not even consider his own welfare first. She then shows Luffy the symbol on her back, and tells him of her past. After hearing that Luffy also hates the Tenryuubito, she offers him use of her ship.

Trivia

 * Boa Hancock has several comparisons to the Greek character Medusa of the 3 Gorgon sisters. Similarities include the ability to turn people into stone (although the methods are very different), the general snake theme, and most obviously, both are one of three Gorgon sisters.
 * Her ability to seduce other men is a reference to Sirens, which would fit her abilities, as a Siren would seduce sailors and lure them to a watery doom.
 * She is one of two women who have claimed to be the "most beautiful", the other being Alvida.
 * It is possible that her name comes from the flowering plant scientific name of a Snowberry, Symphoricarpos Chenaultii Hancock, a plant known for its showy flowers.
 * A second possibility is, that her name comes from famous gardener Ralph Hancock, who built many famous gardens in the 1920s, 30s and 40s. This would fit with the flower theme as the gardener is in a sense, the leader of a garden.