For much of the series's duration, Itachi was reviled by fans for killing his and Sasuke's entire clan, the Uchiha clan. ... In fact, he was ordered to murder them by the leadership of his village to stop a coup d'etat, meaning that he acted in his village's and Sasuke's best interests the whole time.

Did Itachi kill his clan alone?

In a single night, Itachi and Tobi slaughtered the entire Uchiha clan. ... Although he knew his actions were necessary, Itachi could not forgive himself for killing his own family and believed he had to be punished.

Who killed Itachi clan?

Itachi was ordered by Danzo to kill the Uchiha clan. Originally, Danzo tells Itachi that his clan is going to try to overthrow the village government, and must be stopped. The truth is later revealed that Danzo was more interested in obtaining the power of the Sharingan than he was protecting Konoha.