Bartholomew Kuma

Kuma

Bartholomew Kuma is a Shichibukai, formerly a Revolutionary with a bounty of 296,000,000. He was once feared as an extremely vicious pirate, earning himself the title "Tyrant". He is a type of cyborg called "Pacifista" developed by Dr. Vegapunk. Once Vegapunk finished his modifications on Kuma, the Shichibukai was converted into the first complete Pacifista cyborg, with the serial PX-0, and figuratively died in the process.

Dracule Mihawk

Dracule "Hawk-Eyes" Mihawk

Dracule "Hawk-Eyes" Mihawk is a member of the Shichibukai and the first one to be revealed. He is also the current holder of the title, "Greatest Swordsman in the World" and he owns the strongest sword in the world known as Yoru. Mihawk served as Roronoa Zoro's swordsmanship teacher during the two-year timeskip.

Crocodile

Crocodile's outfit during the Impel Down and  Battle of Marineford

Sir Crocodile is the former president of the secret criminal organization, Baroque Works, and the central antagonist of the Baroque Works Saga. He is one of the longest running primary villains of the series, as well as the first enemy to hand Luffy a complete and utter defeat. He is originally introduced as a Shichibukai, but later was stripped of his title after attempting to take control of the desert kingdom, Alabasta. 

He is also known as Mr. 0 as his epithet having a former bounty of 81,000,000.

Boa Hancock

Boa Hancock - "Pirate Empress"

Pirate Empress Boa Hancock is the only female member of the Shichibukai. She is the Snake Princess of Amazon Lily and rules over the Kuja tribe with her two younger Gorgon sisters, Boa Sandersonia and Boa Marigold. 
Her former bounty is 80,000,000.