The world of One Piece has several big powers fighting for supremacy on the seas. As such, countless big organizations have been established over the years, some of which were made to gain more power over territories, and others to protect the said power.
While not all of the organizations are known to be impressive, there are certainly quite a few who can be considered to be a cut above the rest. The very ruling powers of the One Piece world rank among the strongest organizations, with several others trying to either oppose them or repel their influence.
Baroque Works
The Baroque Works is a criminal organization established by none other than Sir Crocodile, one of the former Shichibukai in the One Piece world. Crocodile used them to create unrest in Alabasta and further a civil war for which he planted the seeds.
The organization was loyal to him despite not even knowing his true identity and only referring to him as Mr. 0. The Baroque Works was structured quite interestingly, as right under Mr. 0 and Miss All Sunday were the nine Officer Agents, deemed to be their strongest. The Officer Agents were followed by the Frontier Agents, and then came the Unluckies, the Billions, and the Millions.
Akazaya Samurai
The Akazaya Samurai are the nine retainers of Kozuki Oden who fought by his side until his dying breath. Known to be the strongest of Wano, they include some of the very strongest characters in the story, with each of them being capable of fighting the Yonko Commanders in the One Piece world.
Their ranks include their leader, Kin'emon, who is followed by Denjiro, Raizo, Kiku, Izo, Kanjuro (formerly), Ashura Doji, Kawamatsu, Inuarashi, and Nekomamushi.
Germa Kingdom
The Germa Kingdom is a nation led by the Vinsmoke Family, a family of assassins who have a reputation of being warmongers. Hailing from the North Blue, the Germa Kingdom is quite powerful and technologically advanced. Their generalissimo, Judge Vinsmoke, holds the highest authority, followed by Reiju and Ichiji. They are then followed by Niji, and Yonji.
Thanks to Judge's incredible mind, the Vinsmoke Family has devised ways to clone life and their entire clone army is strong enough to match a nation's might all alone, as seen in Whole Cake Island.
Cipher Pol
The Cipher Pol is a secret intelligence agency of the World Government that take on tasks such as assassination, espionage, and investigation. Cipher Pol has seen several groups established over the years with CP1 through 8 being their official groups.
CP9 exists as a special group with the license to kill anyone, and they usually work in the shadows with nobody realizing their true identity. The Strongest Cipher Pol group is the CP0, who are directly working for the Celestial Dragons, and among them, the members with masks are said to be the absolute strongest.
SSG
The Special Science Group, also known as the SSG, is a newly established organization that was created by the genius scientist Vegapunk, possibly after years of work on the Pacifista Project. Currently, it is unknown what exactly this organization is all about, however, they're deemed to be a worthy replacement for the Shichibukai, meaning they're at least just as powerful as them, if not stronger. In the future, fans will get an overview of how the SSG functions.
Shichibukai
The Shichibukai, also known as the Seven Warlords of the Sea, is a former organization that consisted of some of the most powerful pirates in the One Piece world. Instead of being opposed to the World Government, however, the Shichibukai were allied with them and in return, gained quite a lot of freedom on the seas.
The organization has no ranks and every one of them is considered to be dangerous in their own way. The Shichibukai were quite mighty and the especially strong ones among their ranks were Dracule Mihawk, Boa Hancock, and Edward Weevil.
Revolutionary Army
Known to be one of the major powers of the One Piece world, the Revolutionary Army is led by Monkey D. Dragon. Their aim is to destroy the current system of the world. This goal sees the Celestial Dragons take all the power and fight for freedom and justice.
The Revolutionary Army is quite powerful and their ranks include some powerful commanders. Dragon is followed by his Chief of Staff, Sabo, and then the Commanders. There are also captains in the group, such as Koala and Hack.
Worst Generation
The Worst Generation is a term used to collectively refer to the current generation of pirates who arrived on Sabaody Archipelago shortly before the Paramount War, along with Blackbeard.
The group is known to be incredibly dangerous and in their ranks are those who are either already Yonko, or are challenging the Yonko. The likes of Blackbeard, Luffy, Law, and Kid are known to be the strongest the Worst Generation.
Marines
The Marines are a major power in the world of One Piece and quite easily the most influential one on the seas. They're the military face of the World Government, meaning they're quite incredible in their job. The ranks of the Marines are quite complex, with a Fleet Admiral being established at the top.
Under him are the Three Admirals, known to be the strongest military force of the Government. Under the Three Admirals are the many Vice-Admirals, who are then followed by the Rear Admirals. There are also other lower ranks such as Commodore, Captain, Commander, and more.
Yonko
The Yonko, also known as the Four Emperors of the Sea, are the four strongest pirates in the One Piece world. They're known to be the rulers of the New World and, until recently, they reigned supreme in the second half of the Grand Line.
The Yonko have some of the biggest armies in the entire world, and thanks to their incredible influence, they have several territories under their protection. Currently, the Yonko include Kaido, Big Mom, Shanks, and Blackbeard.