6. Indra Ōtsutsuki-
Indra was the son of Hagoromo Ōtsutsuki. He was a genius since his birth. But, he was manipulated by Black Zetsu and thus, he changed drastically. His chakra was very evil and he gave off a very dark aura.
The Ten Tails was the embodiment of Kaguya Ōtsutsuki. Its legend is affiliated with the Sage of Six Paths. The Jūbi’s attacks were destructive enough to change the entire landscape. Also, its power is considered immeasurable as it can use natural energy as well.