Kokuō (Ten Tailed Fox)

The Five-Tailed Dolphin Horse (五尾のイルカ馬, Gobi no Irukauma) is a tailed beast formerly sealed within Han from Iwagakure. It was then captured, extracted, and sealed by Akatsuki. After Akatsuki fell, it fell into the hands of Konan in Amegakure, who sealed it in a, yet unnamed, ninja of that village.

Background
According to Madara Uchiha, the Five-Tails first came into being in the waning days of the Sage of the Six Paths' life; to prevent its resurgence, the Sage split up the chakra of the Ten-Tailed Beast into nine separate, monstrous constructs of living chakra, which would become known as the tailed beasts. The Five-Tails eventually fell into the possession of Amegakure and was sealed into an unnamed shinobi there.

Appearance
The Five-Tails primarily resembles a white horse, but its head is based off of a dolphin with two long and short horns.