Rinnegan

The is reputed as the most exalted eyes amongst the, the others being the Byakugan and the Sharingan. Rinnegan wielders are said to be sent down from the heavens to become either a "God of Creation" who will calm the world's disorder or a "Destroyer" who will reduce everything to nothingness. Rinnegan are characterised by light purple sclerae and irides with a ripple-pattern that spreads over the eyeball.

Acquisition
The Rinnegan was first manifested by Hagoromo Ōtsutsuki, inherited as a kekkei mōra from his mother's Rinne Sharingan. With his Rinnegan he saved the world from the Ten-Tails and created ninshū, the precursor of modern ninjutsu. For his contributions to the world, Hagoromo became revered as the "Sage of the Six Paths" and rose to mythological status through the centuries, with his Rinnegan coming to be deemed by many a legend or a mutation.

The Rinnegan can be awakened by combining the chakra of Hagoromo's sons, Indra and Asura, in order to create Hagoromo's chakra. Black Zetsu spent centuries attempting to do so, trying to manipulate the reincarnations of Indra and Asura to awaken the Rinnegan. It was not until the time of Madara Uchiha - Indra's reincarnation - that Black Zetsu was successful, when Madara infused himself with the DNA of Hashirama Senju - Asura's reincarnation. However, Madara's Sharingan did not become Rinnegan until decades later, at the end of his natural lifespan; this also seemingly restored the eyesight lost from his use of Izanagi. When Kabuto Yakushi reincarnates Madara, he operates under a similar hypothesis that Sharingan can be evolved into Rinnegan through combination with Hashirama's DNA. To that end he successfully recreates Rinnegan in Madara's reincarnated body, though these imitation Rinnegan do not have full access to the original's abilities.

Sasuke Uchiha's left Sharingan becomes a Rinnegan when Hagoromo's spirit gives half of his power to Sasuke. His Rinnegan has six tomoe split between its first two ripples. Sasuke is still able to use the powers of his Mangekyō Sharingan.

As with any dōjutsu, Rinnegan can be transplanted into others. Madara implants both of his into Nagato without the boy's knowledge, and Nagato is able to make effective use of the Rinnegan throughout his life due to his Uzumaki lineage. After Nagato's death the Rinnegan are taken by Tobi, who implants the left into himself and hides the other because he can't handle the power of both eyes at once. Even so, he is able to use the one Rinnegan to devastating effect in the Fourth Shinobi World War. Madara reclaims both of his Rinnegan after he is revived and ultimately dies with them.

Abilities
The Rinnegan grants the wielder a wide range of abilities without any known chakra requirements to keep the eyes active. Certain abilities are only available to the original owner of the Rinnegan, but even then the possession of two transplanted Rinnegan can grant overwhelming power. Rinnegan are able to see chakra and its flow within the body, but cannot detect it through obstructions such as smoke bombs. With the Rinnegan, the wielder can master any jutsu and basic nature transformation with ease. A Rinnegan user is able to create chakra receivers, into which they can transmit their chakra across long distances. Rinnegan can also be used to decipher the full contents of the Naka Shrine.

Possessing the Rinnegan grants the user a family of abilities collectively known as the Six Paths Techniques: the gravitational powers of the Deva Path; the menagerie of summons available to the Animal Path; the limitless absorptive potential of the Preta Path; the control over others' souls with the Human Path; the different options of mechanisation in the Asura Path; access to the King of Hell through the Naraka Path. (Nagato distributes these abilities across his Six Paths of Pain by embedding corpses with his charka receivers.) A seventh ability, the Outer Path, is said to allow the user to preside over life and death so that they may revive the dead, control the Demonic Statue of the Outer Path, and through it manifest chakra chains to bind others.

Certain Rinnegan abilities have only been demonstrated by single users: Madara can perform Limbo: Border Jail to create corporeal shadows which are only visible to the Rinnegan; Sasuke's Rinnegan allows him to shift spaces within a certain range of himself.

Trivia

 * is the Japanese term for Samsara, the cycle of reincarnation or rebirth in several Indian religions. This is reflected in the names of all Six Paths of Pain, which share their names with the six Samsaric realms of reincarnation.
 * The kanji is also used in Sharingan and Rinne Sharingan, potentially linking the three terms etymologically.
 * The anime depicts the Rinnegan as being multicoloured in its first few appearances. This is corrected after the Rinnegan starts being depicted in colour in the manga. However, whereas the Rinnegan in the manga is a uniform shade of purple, the anime tends to make the centre-most ring a slightly darker shade of purple.
 * Prior to Sasuke's Rinnegan appearing in colour illustrations by Masashi Kishimoto, the Naruto: Color Edition depicts it as being red. This is corrected in subsequent chapters.
 * In Naruto: Shippūden episode 203, the Sage of the Six Paths' Rinnegan are shown as red.