25 Biggest Mysteries In Onepiece

25- Zoro's Father and Mother and his hometown?
Zoro must be the only character whose backstory has yet to be revealed. Just like how sanji's backstory has been revealed to us. It seems the only person whose backstory to be reveled next will be of zoro. His father mother and hometown will maybe revealed to us in the near future.

24- Void Century and What happened in Void Century:-
The Void Century is a century-long gap in recorded and archaeological history, the study of which is forbidden by the World Government. These events occurred 800 to 900 years before the current storyline. It was hinted at during the Skypiea arc; the dates were seen in Robin’s flashback. Usually Void Century is always mentioned when Will of D. is also mentioned.23- Where do Devil Fruit come from?
22- Who is “Joy Boy”?
 Joy Boy was a man  who played an important role in the history of Fishman Island. He was first mentioned on the Ryugu Poneglyph read by Nico Robin while at the Sea Forest. Since then he has got lot of fan popularity along just like Noland the liar in onepiece.
21- Powerlevel of the Gorosei? 

 
The Gorosei (“Five Elder Stars”) are the heads of the World Government. They are the five men who rule above the Marines, Cipher Pol, and the ones who made a pact with the Shichibukai. So far, none of their names and other information has been revealed yet in both anime and manga.
20- How Blackbeard acquired multiple devil powers?
During Marineford Blackbeard was shown stealing and using whitebeard's devil fruit power Gura Gura No mi when he already had already eaten Yami Yami no mi. It has already been mentioned that a person cannot have two devil fruit powers at the same time. But Blackbeard showed us using two devil fruit powers at the same time. This has been one of the biggest mysteries in onepiece.
19- Members of The Revolutionary Army and their goal?
18- Monkey D. Dragon's Devil Fruit Ability:-
It has already been shown to us in many instances that dragon does have devil fruit powers but it has not been officially exposed to all of us. Nothing related to his powers have been revealed yet.    
17- All Blue
Although All Blue has been mentioned many times in onepiece as it is sanji's dream to find all blue,No Information related to it has been revelaed yet in onepiece.
16- Who is luffy's mom? Is she alive?
15- Ancient Weapons Uranus, Pluton and Poseidon? What do they look like and how powerful are they?
14- Voice of all Things and who can hear them?
The voice of all things is mysterious phenomenon in the world of One Piece. It was first mentioned by Silvers Rayleigh when he revealed that Gol D. Roger had the ability to hear it. It is said that also Kozuki Oden had this ability. Princess Shiraoshi, Momonosuke and Monkey D. Luffy have this ability too.
13- Owner of the last Road Poneglyph
As we know the combined locations detailed by all four Road Poneglyphs, allows one to locate Raftel. The first Road Poneglyph is on Zou inside the Whale tree. The Second Road Poneglyph is currently within the possession of Charlotte Linlin. A copy of it is currently in the Straw Hat Pirates’ possession. The third Road Poneglyph is currently within the possession of Kaido. The last Road Poneglyph is currently considered lost. 
12- Will of D.?

11- Shanks True Powers.Does Shanks have a Devil Fruit Power?
10- Did Gol D.Roger have a devil fruit power?
9- Is BenBeckman Swordsman? How powerful is he?
Benbeckman who is the vice captain of the Redhair pirates is said to be the most intellegent person having greates IQ in Onepiece. Although he has been shown as a man using gun he has also been shown using his gun just like a sword and was also paired with Shiryu during marineford war.

8- Why jewelry Bonney was crying when whitebeard and ace died?Did she have connection with them?
After Marineford war Jewelry bonney was shown to be crying. But it has still not been shown for whom she was crying. It was among whitebeard or ace. After that she was shown trying to gain revenge on blackbeard but was badly beaten and was caught by Akainu.

7- Edward Weevil's Power that even kizaru said is very powerful? Is Weevil Whitebeard son?
Edward Weevil has been shown to be targeting whitebeard pirates and taking them down. He has also been given the status of a warlord. Even Admiral Kizaru admires the power of Edward Weevil and compared him to young whitebeard.

6- Does Commander in Chief Kong have Devil Fruit Powers?How powerful is he?
5- What is the reason behind Zoro closing his Eye and cut in the eye? Is there any connection between Zoro and Rayleigh as they both are swordsman and both have cut in their eye?
4- Why do Celestial Dragons wear Space Helmets? Why are they so important and the reason behind their political power?
3- How did Shanks arrive fast to marineford when he was trying to stop Kaido just before the war?(timetravel theory from many guys:D)
2- Admiral Greenbull and his powers
1- Legendary Treasure "Onepiece":-
Legendary tressure onepiece is the treasure around which the entire story of onepiece anime revolves. It was found by Gol D.Roger and his crew members and is believed to be hid by them.