Legendary Creatures

Legendary Creatures are a group of incredibly rare, and often very powerful animals in the Ninja World, the most famous of the creatures being the nine Tailed Beasts.

While on the main continents, all are typically grouped under the banner of "demons", there are three distinct terms that are used to refer to them. One, 伝説のポケモン (densetsu no yōkai), literally "Demons of legend", refers to creatures such as the Tailed Beasts and Kitakaze, who are featured prominently in the legends of the Shinobi world. A second, 幻のポケモン (maboroshi no yōkai), literally "Demons of illusions", refers to demons seen so rarely, such as the Ten-Tailed Beast, that some question their very existence. The third and newest term is 神話のポケモン (shinwa no yōkai), literally "Demons of myth", which refers to the creatures which are spoken of as the creators of the Land of Mountains.

Tailed Beasts
The tailed beasts (尾獣, bijū) are giant demons that serve to drive the plot of the Naruto series, referred as "Chakra Monsters" because they are actually living "ultimate chakra", far beyond a normal human's and given physical form. Because of their power, the tailed beasts served as weapons and tools used in Ninja Wars until it ended and several of the tailed beasts were distributed by the First Hokage amongst the five ninja nations as a peace treaty, in order to stabilize the balance of power between nations. Each revealed tailed beast is over 100 meters tall. They are differentiated by the number of tails they have, with each possessing an amount from one to nine. However, this immense strength is tempered due to their bestial nature, which restricts some of them from being smart enough to use it effectively as seen with the three-tailed beast. Beasts sealed within another person are able to benefit from the knowledge of their hosts, giving them the ability to speak and better utilize their powers.

Akatsuki is currently collecting the tailed beasts, capturing the hosts and taking them to a secret location where a three-day-long jutsu is performed to draw out the tailed beast from the host. They possess seven of the nine tailed beasts: Shukaku, the one-tailed tanuki (extracted from Gaara); the two-tailed demon cat (extracted from Yugito Nii of Kumogakure); the turtle-like three-tailed beast (whose previous host was a young boy from Kirigakure); the four-tailed beast (extracted from Roshi, an elderly ninja from Iwagakure); the five-tailed beast (extracted from a tall male shinobi from Iwagakure); the six-tailed beast (extracted from a young man of unknown origins); and the seven-tailed beast (extracted from a kunoichi from Takigakure). Only the eight-tailed beast (an ushi-oni-type creature sealed within a man from Kumogakure known as "Killer Bee") and the nine-tailed demon fox (sealed within Naruto Uzumaki) remain to be captured. The Akatsuki leader, Pain, claims that when all nine beasts are sealed, he will be able to create a jutsu powerful enough to instantly wipe out a country.

The Slabias
The Slabias are three demon birds reffered to as The Slabia of Darkness, The Slabia of Light, and The Great Slabias. Once, they all bestowed their Sharingan Kekkei Genkai to the Uchiha Clan. One specializes in evil and the other in good, and the third's abilities are unknown. They have even passed down the ability to summon them in battle, (a techinque known only by the Uchiha clan), however, the only one ever sucessful was Obito Uchiha. There have been many thoughts of the Sharingan's bestowance to the Uchiha clan, but this is the true one.

The Doyō
The Doyō (土用, doyou) are a group of six dog-like creatures that inhabit the Land of Mountains. They are also called the Legendary Dogs (伝奇的犬, densetsu no inu). The people of the Land of Mountains refer to these beasts as the origin of each Elemental Transformation of chakra. All six have two natures and can combine these natures at will to form Kekkei Genkai. Unlike the Tailed Beasts, they aren't malicious chakra in beast form, but actual living creatures. Also unlike the Tailed Beasts, they are unable to be sealed in hosts, preventing anyone from controlling thier power at will.