Monkey D. Luffy met pirate hunter Roronoa Zoro early on in One Piece. Despite his skills and experience as a swordsman, Zoro had gotten himself captured, and as a lone warrior, he refused at first to join Luffy. Then he changed his mind, and has served as Luffy's loyal, no-nonsense swordsman ever since.
Source:https://www.cbr.com/anime-characters-similiar-to-one-piece-zoro/