It was recently confirmed that One Piece manga will be entering the final saga soon. This means that the series is nearing its conclusion and many mysteries will be unraveled. This also confirms that all the remaining big names will be involved in this saga.
It is clear that there are still many characters, who are yet to be involved in One Piece. Some of them have been introduced multiple arcs ago, but they haven't been heavily involved in the series yet. As the final saga is coming up, Eiichiro Oda will have the opportunity to reveal their powers and their real motives.
8 Shanks
Shanks is very important to the story of One Piece as he was the person who inspired Luffy to set out on his journey to becoming the Pirate King. Since his last meeting with Luffy, a lot of things have changed.
Back then Luffy was just a crybaby with big dreams, and presently, he is comfortably one of the strongest characters in the series. Shanks' powers and goals are still mysterious, so there is no doubt that Shanks will play a crucial role in the final saga.
7 Five Elders
The Five Elders or the Gorosei are considered to be the sovereigns of the World Government. They are extremely knowledgeable about the past, which includes the mystery of D., and the Void Century. It is obvious that both of these things pose a threat to their authority, so the Five Elders ensure that the rest of the world does not find out about it.
The Five Elders have taken many measures over the years to protect their secrets. There is no doubt that the World Government will get involved at some point, and after failing to get their hands on Luffy's Hito Hito no Mi, Model: Nika, they will have to take immediate action.
6 Monkey D. Dragon
Monkey D. Dragon is the leader of the Revolutionary Army. He is the most wanted criminal in the series, and it is about time that he makes a move. Dragon wants to liberate the entire world from the shackles of the World Government, and he has already managed to free a few nations.
The fans know absolutely nothing about Dragon, but that will definitely change in the upcoming arc. It has been heavily implied that the Revolutionary Army members in Mary Geoise were involved in some kind of mishap, which might force Dragon into making a move.
5 Akainu and the Marines
Akainu was promoted to the position of Fleet Admiral after he won his fight against Aokiji. Immediately after coming to power, Akainu implemented several changes and the biggest one among those was the decision of moving the Marine Headquarters closer to the Red Line.
Once the news of Luffy's exploits reaches the Marines, it is clear that they will have to take action. Also, Luffy still holds a grudge towards Akainu for the killing of Ace. The two of them will undoubtedly clash in the final saga.
4 Blackbeard
Blackbeard became a Yonko after defeating the remnants of the Whitebeard Pirates. He rose through the ranks in a very short period and currently, he is among the strongest pirates in the world. Blackbeard is the only character in the series with two devil fruits, which makes him a very dangerous opponent.
Blackbeard has been very secretive about his ambitions and ever since the time skip, he hasn't been heavily involved in the series. As the manga moves into its final saga, the fans will surely see Blackbeard and his crew in action.
3 Monkey D. Luffy
Monkey D. Luffy is the main protagonist of the series. In the Wano Country arc, Luffy finally managed to defeat Kaido, which brought an end to the reign of terror. Luffy is getting closer and closer to his goal of becoming the Pirate King, and it won't be a stretch to say that he has never been closer to his dream.
Along with becoming the Pirate King, there are some other things that Luffy needs to take care of. He needs to topple the wicked World Government, take down the remaining Yonko and finally reveal the secret of the Void Century to the world.
2 Shirahoshi
Shirahoshi made her debut in the Fish-Man Island arc. In the arc, it was revealed that Shirahoshi is one of the three Ancient Weapons, namely, Poseidon. Her power allows her to control the Sea Kings, who are capable of destroying entire islands.
It was revealed that Joy Boy had made a promise to Poseidon, but due to several reasons, the promise could not be fulfilled. The new Joy Boy and Poseidon have already met each and there is no doubt that the two of them will try to complete the promise that was made centuries ago.
1 Im
Im is the actual leader of the World Government. As seen in the Reverie arc, the Five Elders respect every wish of Im and they wait for his orders so that they can carry them out. Im has a lot of secrets, and it is unknown how came to power and how he got his hands on the giant straw hat. There is no doubt that Oda will reveal all the mysteries associated with him in the final saga.