Naruto Begins by Cracking Uncle Snake's Secret Cabin

Speaking of the early villains in Naruto, Orochimaru is definitely a BOSS-level existence. He defected from the ninja village, assassinated the third generation of Hokage, attempted to get his hands on the blood chakra eye, and colluded with Danzo, the founder of the Root Organization, to develop a series of forbidden human techniques. Orochimaru is a controversial figure. His character is not to be praised, but the forbidden techniques he developed are very easy to use. Even ordinary ninjas can exert their super strength. Orochimaru's mysterious base is definitely comparable to the great treasure of One Piece!