Naruto is filled with interesting and unique characters, and most of them are ninjas. Most of these ninjas are skilled fighters, but there are certain individuals who are extremely powerful. Each of the Five Great Nations is led by a Kage who is considered their village's strongest ninja, and Hiruzen Sarutobi served as the Leaf Village's Third Hokage.
Source:https://www.cbr.com/naruto-ninja-stronger-the-third-hokage/