To be a used BOSS in Naruto series, we have to admit the ability of Orochimaru, own the same power with Jiraiya and Tsunade, he once was a kindly guy in Konaha. But finally addict to the research
of living forever and use the alive ninja to experiment and finally escaped from Knoha and his teacher Thir Hokage.
After combine with another country, he try to destory Konoha with his new body. Even the new ability has not finished yet, he start to his project and have a fight with third Hokage and killed him after sacrificed his two hand, I really cannot understand his feeling when he kkilled his teacher. He want to have an Sharingan and used to attack Itachi but beated by Itachi in a seconds by the illusion. He take use of the revenge of Sasuke and try to make Sasuke more strong than everyone and then garb his body but finally killed by Sasuke. When Sasuke conflict with Itachi, he came out from Sasuke's body still want to control them and get the eyes, but reeled by Itachi.
Orochimaru is a genius actually, he can use all kinds of Ninjutsu and with horrible ability. Even though beated by Itachi by from the latest chapter in manga, we know that he know many secret about Sharingan and Rokudo sennin. And he still alive in Kabito's body in any means.