Orochimaru is a main villain in the Naruto series and plays a pivotal role for many of the characters. He first appears in the series when he gives Sasuke Uchiha a curse mark that affects him for the rest of his life by allowing him to tap into incredible amounts of power at the cost of wanting more which Orochimaru wants to use to get Sasuke to join him. His reason for this was revealed to be selfish as he wanted Sasuke for his body so that he could take it over and gain the Uchiha's unique power, the sharingan.
During the Chunin exam (the events shown in mostly every Naruto game released recently) he leads an assault on the Village Hidden in the Leaves (Konohagakure) with his village (the Village Hidden in the Sound) and the Sand village, but betrayed the Sand for his own personal goals. He fought his former master, the Third Hokage, and loses the use of his arms during the battle (also at the cost of his former master's life) and seeks a healer.
He seeks out Tsunade (who formerly trained with Orochimaru) and asks her to restore his arms and he will resurrect her brother and lover from the dead. She is about to kill him but is interupted by his assistant, Kabuto, and they start to fight. Eventually Naruto and Jiraiya meet up with them and aid Tsunade in the fight. Orochimaru and Kabuto are forced to retreat and go into hiding. Soon after Sasuke leaves Konoha to join Orochimaru to gain more power to use against his brother Itatchi. Before Sasuke can reach him he has to take over the body of a servant of his to continue living as part of his immortality jutsu where he can take the body someone in order to increase his lifespan but is still able to retain his regular appearance. Two and a half years later Orochimaru needs another body and begins preparations to transfer into Sasuke's when Sasuke kills him. Kabuto was devastated by this and surgically integrated Orochimaru's remains into his own body. Orochimaru slowly is taking over Kabuto's body.
In the video games his moves usually revolve around snake attacks, fire breathing and more recently the sword that he keeps in his throat. He is known for being one of the more powerful characters like fellow Sanin Jiraiya and Tsunade.