Kabuto Yakushi

Kabuto Yakushi (薬師カブト, Yakushi Kabuto) is a major antagonist of the series, who was first introduced as a Konohagakure genin. He was orphaned by war as a child and was found by Nonō Yakushi and raised in the Konoha Orphanage. After joining Root, he served as a deep cover agent in different countries for several years before defecting and joining Orochimaru, where he acted as his personal medic, research assistant, and general right-hand-man. During the Fourth Shinobi World War after Orochimaru's sealing, Kabuto joined forces with Tobi and Akatsuki

Naruto (c) Masashi Kishimoto