Crocodile

Crocodile, also known as The Crocodile (サー・クロコダイル) or Mr. 0, is implied to have a varied and decorated career as a pirate and once desired to become the Pirate King like Luffy. He shared some connections with Emporio Ivankov and lost to Whitebeard once in the past. Six years before the main story begins, Crocodile offers Robin shelter from the law in exchange for her service to read Poneglyphs, or ancient historical records written in a lost language.

Over the years Crocodile gains enough prestige to be one of the Seven Warlords of the Sea, or a former pirate captains who serve under but not necessarily respect the World Government. Abusing the privileges that come with his title, Crocodile creates his station at Alabasta Kingdom. He uses a magical item called Dance Powder to brainwash Alabasta's people to accept him as the true hero of Alabasta and secretly leads a formidable espionage group, Baroque Works, to assassinate people who learn the truth and intimidate any of his oppressors. Although he looks forward to breaking the king's adamant defiance to him, Crocodile ultimately desires to gain access to the royal family's vault and obtain information regarding the legendary weapon of mass destruction, Pluton. He needs Robin to translate the Poneglyph describing the weapon for him.

Despite overpowering Luffy during their first standoffs, Crocodile is defeated by the pirate captain. He is striped of his titles and sent to the underwater prison, Impel Down. He joins the eventual prison break with the sole desire to avenge his past defeat to Whitebeard.

Personality
An egotist who believes only in himself, Crocodile works with others to fulfill his selfish ambitions. His masterful perceptiveness embellishes his cutthroat reputation with his business deals. Crocodile knows who he wants to use and when he wants them near him. He aggressively barters with those he deems will be useful for his schemes, but he will immediately dispatch anyone once they have served their purpose to him (including his own subordinates). His Devil Fruit powers further boosts his ego, as he proudly brags that he is invincible to pain. Despite his cold-hearted, arrogant, mob boss attitude Crocodile can be surprisingly aloof with his decisions. If a prospect doesn't rile him, he'll be indifferent to it.

Fighting Style
Considerably strong in his own right, Crocodile's strengths multiply with his Devil Fruit. It allows him to turn his entire body into sand, making him resilient or invulnerable to many attacks. The sand can be used to generate disposable projectiles, create damaging sandstorms, or to slice the ground apart. He can also instantly suck the moisture from any object or lifeform he touches. It can cause anything within his grasp to severely wither or, in extreme cases, deteriorate to nothingness.