1. Uchiha Itachi: Itachi's true strength is still unknown as he held back during his fight with Sasuke and only used reserved techniques in the Fourth Great Ninja War. He may still have untapped potential.

2. Akasuna no Sasori: Sasori's puppetry skills are considered the best in the ninja world. He intentionally held back during his fight against Chiyo and Sakura and only used three out of the four scrolls on his back. The fourth scroll possesses devastating power.

3. Uchiha Izuna: Izuna's eye abilities are immeasurable, but he never engaged in battle and died at the hands of Itachi. His special abilities with his Mangekyou Sharingan remain unknown.

4. Jiraiya: Jiraiya's official stats make him a Kage-level figure, but his true power may not have been fully displayed. It is estimated that his power will be revealed through the character "Kashin Koji" in "Boruto: Naruto Next Generations."

5. Sakumo Hatake: Known as the "White Fang of the Leaf," Sakumo's combat abilities were never shown. His swordsmanship and ninja arts remain a mystery.