Naruto is one of the "Big Three" of the Shonen Jump. Written by Masashi Kishimoto, the manga is among the most popular series in the world. Naruto has many interesting characters who always provide great entertainment to the viewers. Kishimoto deserves a lot of credit for the work that he has put into the series.
But just like any normal person, Kishimoto has committed his share of errors, which are reflected in the story. He is notorious for his habit of killing great characters just to further the plot. While it may have been unavoidable sometimes, there were instances where he could have taken another direction and ensured that these Naruto characters would have lived on for longer than they did.
7 Itachi Uchiha
Itachi Uchiha is one of the most beloved characters in the series. For the most part, he was portrayed as an evil villain who massacred his entire clan and tortured his young brother. The truth didn't come out until after his death when Obito told Sasuke about what had actually occurred.
Itachi had been carrying all the guilt by himself, and he tried his best to protect Sasuke from all kinds of threats. Aside from fighting Sasuke, fans never got an opportunity to see him in action properly, and considering Itachi's backstory, he should have had more time on the screen.
6 Zabuza
Zabuza was one of the Seven Swordsmen of the Mist. From a young age, Zabuza had a knack for bloodshed, and when he was pitted against multiple ninjas older than him, he killed all of them. As he grew up, Zabuza left the village and became a mercenary.
He was the first strong villain that Team 7 faced in the story. Zabuza gave them a run for their money, but he was outclassed by Kakashi. Zabuza also had a change of heart after he heard Naruto's speech about how Haku protected him to the very end. If Kishimoto had left him alive, Zabuza could have come back as an ally in the future, or he could have received a side story of his own.
5 Neji Hyuuga
Neji Hyuuga was killed in the most bizarre way possible. During the Fourth Great Ninja War, when the Ten-Tails shot some projectiles toward the heroes, Neji decided to throw himself in the way, which led to his death. Neji was killed for the sake of romance, and it was rather poor writing from Kishimoto.
Neji was a Jonin and a prodigy of the illustrious Hyuuga clan, so to end his life in such an odd way did not go down well with fans. The author could have easily kept him alive and used him in Boruto. Neji could have become the leader of the Hyuuga clan and changed all the old reforms.
4 Kimimaro
Another character who was wasted, Kimimaro, belonged to the Kaguya Clan, which was known for waging wars. Unlike the other members of his clan, Kimimaro was not interested in fighting, so he barely used his kekkei genkai.
Eventually, Kimimaro met Orochimaru, who became interested in his body. Kimimaro had immense fighting potential, and he could have become one of the strongest characters in the series. However, Kishimoto handled him poorly. He gave Kimimaro an incurable disease, which conveniently led to his death just before he could finish Gaara and Rock Lee.
3 Shisui Uchiha
Shisui Uchiha was among the few Uchiha who were more loyal to their village than their clan. He was considered the strongest Uchiha of his time, and his strength was renowned throughout the ninja world.
For someone with so much fame, Shisui's contribution to the story was pretty disappointing. He was not involved in any major fights, and his backstory was kept to a minimum as well. Shisui couldn't react to an attack by Danzo despite being one of the quickest ninjas of his time. After running away from Danzo and his underlings, Shisui could have still played an important role, but Kishimoto decided it would be better to make him commit suicide.
2 Minato Namikaze
Minato Namikaze was the Fourth Hokage of the Hidden Leaf. He was a genius, who breezed through the Hidden Leaf's Academy. After becoming a Jonin, it didn't take long for Minato to make a name for himself. He spearheaded the Hidden Leaf to victory in the Third Great Ninja War.
His contributions made everyone in the village appreciate his skill, and eventually, he was chosen to become the Hokage. Sadly, Minato's reign didn't last for long, as Obito decided to attack the Hidden Leaf with the Nine-Tails. Minato had to sacrifice himself to protect the village and his son, but many fans believe that it was completely unnecessary. From Minato's interaction with Kushina, it is clear that the former chose to sacrifice himself because he believed in Naruto. In other words, he was killed to advance the plot.
1 Haku
Haku's story is a tragic one. He had a good family, but things changed when his father found out about his kekkei genkai. Haku ended up losing everything, and he was left with no support at all. In the end, Haku was taken in by Zabuza, who only wanted to use his power.
Zabuza trained Haku, and the latter became his personal bodyguard. Haku met his end when he jumped in front of Kakashi's attack that was meant for Zabuza. While it was an emotional moment, if Haku had not been killed, he could have become a splendid ninja. Furthermore, fans would have gotten to see more Ice Release techniques.