Koby

Luffy's first friend, the chore boy who became a Marine hero.

Koby is a Marine in One Piece and the very first friend Luffy makes on his voyage, met while Koby was stuck doing chores aboard Alvida's ship.

Quick Facts

Affiliation: Marines
Rank: Captain (after the time skip)

Facts from the source article.

Background

With Luffy's help, and fired up by his example, Koby gets away and enlists in the Marines alongside Helmeppo, and Vice Admiral Garp decides to train the pair personally. Koby learns Shave, one of the Six Powers, picks up Color of Observation Haki and by the end of the two-year time skip holds the rank of captain. The Rocky Port Incident made him a hero: there he grudgingly cooperated with Trafalgar Law and Blackbeard to defeat Wang Zhi. Later, after a clash involving Blackbeard and Boa Hancock, he is taken to Fullalead, where Garp arrives to rescue him.