Sasuke Uchiha: Sasuke's power significantly increased in the later stages, especially after obtaining the Mangekyou Sharingan. He can be called one of the strongest in the ninja world, on par with Naruto. He single-handedly took on and sealed all nine-tailed beasts using his eye technique, the Amaterasu, earning the title of defeating the most-tailed beasts at once.
Gaara of the Sand: Gaara, the third and fifth Kazekage, father of the fifth Kazekage, is highly skilled in using his bloodline limit. With his Magnet Release, he can manipulate sand and is virtually invincible in the desert. He once fought and completely suppressed Shukaku, the One-Tail, in the desert. Gaara is also a great leader.
Hashirama Senju: The first Hokage and one of the founding members of Konoha, he engaged in a fierce battle with Madara Uchiha and the Valley of the End. Madara controlled the Nine-Tails during the fight, but Hashirama used his Wood Release to trap the beast and defeat both Madara and the Nine-Tails.
Naruto Uzumaki: The seventh Hokage, Naruto faced off against the Ten-Tails army led by Uchiha Madara during the Fourth Great Ninja War. By merging with the Nine-Tails, Naruto's power greatly increased. He single-handedly battled and defeated six-tailed beasts.
Madara Uchiha: One of the founders of Konoha, the former Uchiha leader, Madara tried to control the Nine-Tails using his Sharingan to defeat Hashirama. However, he was defeated by Hashirama during their battle.