The World Government in One Piece assigns a bounty to an individual depending on the level of threat that they pose. There are other factors that affect the assignment of bounties of an individual. On rare occasions, the bounties of a character may not provide an accurate threat level.
However, the bounties are usually spot-on and give a correct idea of an individual's notoriety. So, a higher bounty implies that the individual is very powerful. There are very few characters in OnePiece that have a bounty of a billion beris.
11 Charlotte Katakuri
One of the Three Sweet Commanders, Charlotte Katakuri is among the strongest characters to be introduced in the series. Katakuri possesses the Mochi Mochi no Mi, which is a special paramecia type devil fruit.
Before facing Luffy, Katakuri had an unbeaten record; he had never lost to an opponent. Katakuri acted as a mentor to Luffy and enabled the latter to become a better fighter. He has a bounty of 1,057,000,000 beris.
10 Queen
Despite his antics, Queen is a highly intelligent individual, who has created many deadly weapons. His fatal viruses earned him the moniker of "Queen the Plague."
Queen has done several modifications to his body, which allows him to catch his enemies off-guard and thus, paves way for a lethal strike. Queen's bounty of 1,320,000,000 beris puts him slightly behind King.
9 Marco
Marco formerly served as the First Division Commander of the Whitebeard Pirates. After Whitebeard's death, Marco took charge and became the captain, but it didn't last for long as the remnants of the crew were easily defeated by the Blackbeard Pirates.
Marco is a very strong character and he was considered one of the few people that could defeat Blackbeard. Marco possesses the Tori Tori no Mi, Model: Phoenix, which is a mythical zoan type devil fruit. He has a bounty of 1,374,000,000 beris.
8 King
He is the strongest All-Star of the Animal Kingdom Pirates. King is an incredible fighter, who can give the strongest of characters a run for their money. Like the other All-Stars, King too possesses an ancient zoan type devil fruit.
His Ryu Ryu no Mi, Model: Pteranodon grants him increased strength and recovery. Furthermore, the devil fruit also grants King the ability to fly. Being a member of the notorious Animal Kingdom Pirates, his bounty of 1,390,000,000 beris is unsurprising.
7 Monkey D. Luffy
Monkey D. Luffy is the captain of the Straw Hat Pirates. Luffy is capable of using all three types of Haki, and he combines Haki excellently with his devil fruit. His exploits during the Whole Cake Island arc resulted in his bounty going up to 1,500,000,000 beris.
This increase in the bounty caused him to be labeled as the Fifth Emperor, that is a mighty title. Currently, Luffy is fighting Kaido, and his bounty is only going to increase further.
6 Blackbeard
Marshall D. Teach, also known as Blackbeard, is considered to be the final opponent that Luffy will face in One Piece. After spending years on Whitebeard's ship, Blackbeard stole the Yami Yami no Mi and killed Thatch. He became a Shichibukai and then after Whitebeard's death, Blackbeard became one of the Four Emperors.
He is already considered a major threat by the World Government and he quite rightly deserves his bounty of 2,247,600,000 beris.
5 Shanks
Often shown to be an easygoing individual, Shanks can become an unstoppable monster if his friends are threatened. Shanks is one of the few characters who can use all three types of Haki.
Shanks' true strength remains to be seen, however, that will change in the future arcs. He is the youngest of the Four Emperors and still has an impressive bounty of 4,048,900,000 beris.
4 Big Mom
Charlotte Lilin is the Queen of Totto Land and she is one of the strongest characters in the series. Big Mom was a part of the legendary Rocks Pirates and after Xebec's death, she started Big Mom Pirates.
Big Mom's strength allowed her to become one of the Four Emperors of the Sea. Her strength is on par with Kaido, and on several occasions, she has displayed her ridiculous powers. Her current bounty is 4,388,000,000 beris.
3 Kaido
Kaido formerly served under Rocks D. Xebec and after the latter's death, he started his own pirate crew. He gained fame in a short time and earned the respect of other pirates with his strength alone.
Kaido possesses the Uo Uo no Mi, Model: Seiryu, which allows him to turn into a giant eastern dragon. Kaido's nigh impenetrable strength makes him dangerous, and the World Government has tried to execute him several times, but they have only been met with failure. Kaido is an infamous pirate, who is only interested in destroying everything and he has amassed a bounty of 4,611,100,000 beris.
2 Whitebeard
Another legendary pirate from the Old Era, Whitebeard earned the reputation of being the Strongest Man in the World. Armed with the overpowered Gura Gura no Mi, Whitebeard was deemed to have enough power to destroy the world.
Whitebeard used to be rivals with Gol D. Roger, and they had immense respect for each other. Whitebeard's monstrous strength made a big threat to the power of the World Government, and they slapped him with a bounty of 5,046,000,000 beris.
1 Gol D. Roger
Gol D. Roger was the only person who managed to reach the final island, Laugh Tale. On his journey to the final island, he managed to learn about the Void Century, which made him the World Government's biggest foe.
Roger's strength was almost unparalleled, and there were only a handful of characters that could actually challenge his might. His strength and his knowledge landed him an astounding bounty of 5,564,800,000 beris, which is the highest known bounty in the series.