Kurama

The Nine-Tailed Fox. Sealed within Naruto by Minato. Initially hostile, Kurama becomes Naruto's true partner after building a bond of mutual trust.

Created by Hagoromo, Kurama is the most powerful of the nine Tailed Beasts. It was split into Yin and Yang halves by Minato. The Yang half was sealed in Naruto; the Yin half within Minato himself. Their complete merger gives rise to the Kurama Chakra Mode, Naruto's peak power before Six Paths.