Yonkō are the four pirates that rule the New World, and are one of the Three Great Powers. These four pirates are extremely powerful, and can do anything they want. If any two Yonkō formed an alliance with one another, it is enough to terrify the World Government. The Yonkō are generally feared because they’re the ones closest to the One Piece. Two of them hold the Road Poneglyphs, 4 of which lead directly to the One Piece.
6. Nico Robin
Nico Robin is a member of the Strawhat Pirates, and a scholar. Robin can read and write Poneglyphs, which she learned when she was a child. After the destruction of Ohara, World Government issued a bounty of 80,000,000 berries for Nico Robin because she knew how to read Poneglyphs. She was almost caught at Enies Lobby, but was rescued by Luffy and the rest of the Strawhats.