Itachi was a ninja of Konoha and later became a member of Akatsuki. After he killed his entire clan, he then infiltrated the Akatsuki and provide information to Konoha of Akatsuki.
He is without a doubt one of the best spies in the anime-world. So, today I have made a list of 6 anime spies who are better than Itachi.
Fukumoto is one of the best agents under Lt. Colonel Yuuki and is from Joker Game. He has many identities at the same time and devoted to the secrecy of his mission. Moreover, he remained faithful to the Lt.
Colonel and the Emperor until the end of the war. He has got every skill that a spy needs and is good at combat.
Arthur Lynch is of the Free Planet Alliance and is from the anime Legend of Galactic Heroes. He is a perfect spy, he can even sacrifice the lives of his own allies for the sake of the mission.