Admiral Aokiji (青雉大将, Aokiji Taishō) is one of the three Marine Admirals. His real name is Kuzan (クザン Kuzan), and he was once a Vice Admiral. He is also a nominee for the position of Fleet Admiral.
His power is so great that he was able to easily overpower Luffy and the other Straw Hats single-handedly. Due to Aokiji's power, the fated conflict between him and the Straw Hats prompted Luffy to be less naive towards future conflicts; for this reason Aokiji served as the starting point for Luffy to push his strength beyond his limits.
Aside from that and his Devil Fruit powers, his physical proficiency is also extremely high, as he is able to repel simultaneous attacks from Zoro, Luffy, and Sanji without taking any damage. He has also been seen jumping to a very extreme height, in order to freeze a pair of tsunamis caused by Whitebeard. He is also able to travel at tremendous speed, as seen when attacking Buggy, whether this is due to him using Soru or his Devil Fruit is unknown. He also has a very good hearing, since he could hear the Moby Dick rising from the water.
Along with this, he is powerful enough to fight against notably powerful figures such as Diamond Jozu, the Third Division Commander of the Whitebeard Pirates, and even Whitebeard himself. He was also acknowledged by Jaguar D. Saul, who had destroyed several huge warships and had lifted one by himself, that Aokiji's strength was abnormal, even before he was an admiral.