The Weakest Villain In All Of Naruto's History
Naruto's conclusion came after 700 manga chapters and an even greater number of episodes due to periodic filler story arcs original to the anime. At the series' core throughout its extensive run was always Naruto, a sometimes aloof but headstrong ninja of Konohagakure village. Naruto was never one to work alone, however. Dozens of side characters would ultimately fight alongside Naruto in the numerous battles to feature in its expansive storyline. Sometimes, and especially in its earliest story arcs, those were fellow members of Konohagakure village. As the series progressed and more of Naruto's world was revealed, ninja from other regions would join Naruto and his ever-growing group of allies, too.
The sheer number of characters featured as protagonists, be they series regulars or limited to a single story arc, is reflective of Naruto's formidable scope. That scope extends to Naruto's villains, too. In order to give its substantial cast something to do, nearly just as many villains as there are heroes have posed a threat to Konohagakure or even the entire world throughout the series' run.
Some of Naruto's villains are near-deities, like Kaguya and the other members of the Otsutsuki clan, who are among the strongest characters in Naruto history. On the other end of the spectrum is Zabuza, the series' first proper big bad and weakest villain all.
Zabuza doesn't live up to his reputation
Zabuza's life prior to the present events of Naruto positioned him as a formidable, dangerous adversary. Over the course of his training to become a warrior for Kirigakure village, Zabuza killed over 100 of his fellow students. The magnitude of his killings ultimately brought an end of a practice wherein future warrior candidates would fight one another to the death. Zabuza then became one of the Seven Swordsmen, who are comprised of the strongest warriors from throughout Kirigakure. However, after a failed coup attempt on Kirigakure's leader, Zabuza fled and became a wandering assassin without a village to call home.
He then served as the Big Bad of the first proper mission for Naruto's Team 7, which included in its opening series mainstays Naruto, Sasuke, Sakura, and team leader Kakashi. Their clash against one another opened with Zabuza trapping Kakashi with an ability called the Water Prison Technique. However, once freed by Naruto and co., Kakashi proceeded to beat Zabuza two subsequent times without much issue.
On one hand, this suggests that Zabuza may not have been quite as formidable as his reputation suggested. On a more metatextual level, Zabuza was merely the first big bad in Naruto history, necessitating that all subsequent baddies should be stronger in order to keep the story compelling. Thus, for one reason or another, the killer of more than 100 fellow students ended up being kind of a pushover.