This article contains spoilers for the One Piece series.
One Piece is in its final saga at the moment, which means that the main characters of the story, the Straw Hat crew, will soon be completed. Right now, aside from Luffy, there are 9 members of the crew, those being Zoro, Nami, Usopp, Sanji, Chopper, Robin, Franky, Brook, and Jinbe. The Straw Hats are already a big crew, but Luffy has, at the very least, one more spot to fill, with potentially more joining. There are quite a few characters that still have a shot at joining the crew of the future Pirate King in One Piece.
Nefertari Vivi
If there’s one character that is guaranteed, at some point in the story, to officially join up with the Straw Hat Pirates, it’s definitely Nefertari Vivi, the princess of Arabasta.
Technically, Vivi is already a Straw Hat Pirate. However, as she chose to stay back on Arabasta 2 years ago, she stopped sailing with the rest and faded into the background. But now, due to the death of her father, King Cobra, and due to her being targeted by the World Government and Imu, Vivi simply can’t return to Arabasta. The only place she can find refuge is with the Straw Hat Pirates. Vivi’s reunion with the Straw Hat Pirates will be an incredible moment to witness.
Jewelry Bonney
Jewelry Bonney is a character that was first introduced in the Sabaody Arc, alongside all the other members of the 11 Supernova. Back then, Bonney was a character many overlooked since she wasn't completely fleshed out, and it took over a decade for her to make a real move in the story.
Jewelry Bonney became relevant again during the Final Saga, and has since Egghead, she's been sailing with the Straw Hat Pirates. Bonney doesn’t have a crew anymore, and she doesn’t really have anywhere to go. Furthermore, Oda has already drawn Bonney wearing a hat similar to Luffy’s once, and in an SBS, he even expressed how she feels safe in their presence and thus stays in her child form more often.
Loki
Loki is a character who was first mentioned in Whole Cake Island, but it took the manga until Elbaf for him to be fully revealed. Loki is pivotal to the overarching plot of the Elbaf arc right now, and fans can’t wait to see what Oda has in store for him.
Loki has quickly become one of the most popular new candidates to join the Straw Hat crew. Luffy has already asked Loki to join. Furthermore, Loki is hated in Elbaf, so he has nowhere to go after being freed. Loki would only really be welcomed by the Straw Hat Pirates, and he would be a huge plus for the crew.
Vegapunk Lilith
Lilith is one of the six satellites of Vegapunk. Each satellite makes up one of Vegapunk’s traits, with Lilith being his evil side. Lilith, aside from York, is the only fully surviving piece of Vegapunk’s mind. The others fused to form one body and will be with Haredes in Weatheria. Since the Egghead arc, Lilith has been traveling with the Straw Hat Pirates, and many believe she could be the next one to join them.
Lilith is a genius scientist, and the Straw Hat Pirates don’t have anyone who truly fulfills this role right now. Lilith could be vital in helping upgrade weapons, the Sunny, or even to develop one of the Ancient Weapons. Lilith has a shot at joining, but she could also choose to remain on Elbaf after the events are over.
Manmayer Gunko
Gunko is currently a major antagonist in One Piece’s Elbaf arc. Saint Manmayer Gunko is a Holy Knight who arrived at Elbaf with Shamrock at the beginning of the arc. Gunko was always immensely dangerous, but her power went on to reach a whole other level after her body was taken over by Imu.
While Gunko is not on the crew’s side at the moment, she might betray the World Government eventually. This is simply because Gunko and Brook have a secret connection which has yet to be fully revealed. Gunko isn’t truly evil and it is clear that she's been brainwashed by Imu somehow. Her relationship with Brook might sway her to the side of the Straw Hat Pirates. As a powerful fighter, and as someone who has information on the World Government, she would be a major addition. It wouldn’t be the first time an antagonist becomes a Straw Hat.
Yamato
Many fans were certain that Yamato would go on to join the Straw Hat Pirates in Wano. After all, Yamato themself asked Luffy to join, and until the very last moment in Wano, it seemed like they were going to sail forward with the Straw Hat Pirates as the new Oden of this generation.
However, Yamato changed their mind, and instead, decided to stay back and protect Wano. With Yamato’s cover story now over, they might now actually be able to sail off. Yamato could go on to catch up with the Straw Hat Pirates. Yamato is extremely powerful, and also a Conqueror’s Haki user. Their power would be vital in the upcoming arcs.