Info:
Orochimaru was created as one of the series' main antagonists.
In the anime and manga, he is a former ninja of the village of Konohagakure and a former disciple of the Third Hokage. As he grew older Orochimaru, along with Jiraiya and Tsunade, collectively became known as the "Legendary Three Ninja" or "Sannin" (伝説の三忍), due to their exemplary ninja abilities.

Much of Orochimaru's arsenal of abilities deals with snakes.
During his time in Konohagakure, Orochimaru distinguished himself as one of the village's most powerful ninja; however, his desire for power led him to obtain a means for immortality by transferring between different host bodies. This desire for a host is one of his driving motivations throughout the series, resulting in his desire to acquire Sasuke Uchiha due to his powerful genetic heritage.

Source:Wikipedia