Higuma

During the childhood of Monkey D. Luffy (covered in the first chapter of the manga and a flashback early on in the anime), Higuma was a mountain bandit, leader of a band of similar bandits. The band swept into the town where Luffy lived and demanded grog, only to find that the last of it had been purchased by Red-Haired Shanks and his crew. Higuma personally insulted Shanks before storming out of the town; while Shanks laughed it off, Luffy was furious that Higuma had disrespected his hero.

Shortly afterward, while Shanks's crew was out on a voyage, Higuma and his band returned to town. While drinking at the same pub where they'd caused trouble before, Higuma insulted Shanks behind his back - and in earshot of Luffy. Infuriated, Luffy attacked the bandit, only to be thrown down and beaten by the entire group of bandits. Undaunted, Luffy insulted Higuma, and the bandit tried to kill him.

He was interrupted by the return of Shanks and his crew. Seeing what the bandits were doing to Luffy, the pirates attacked and defeated them, driving most of them back into the mountains.

Higuma, though, had escaped with Luffy in tow. He set out to sea, reasoning that given his attitude towards pirates, no one would look for him on the water. He then kicked Luffy out to sea, knowing the boy couldn't swim due to the Devil Fruit curse.

Immediately afterward, however, a Sea King rose from the waters. Higuma, terrified, could do nothing as the creature destroyed his boat and devoured the bandit with one bite.

Before his death, Higuma bragged about having an 8,000,000 beli bounty on his head; he carried his own "Wanted" poster to prove it. This is the first mention of bounties in the manga. This can be considered unintentionally humourous, since he was bragging about it to Shanks, whose bounty is bound to be much higher than Higuma's.