Rinnegan

The is the most revered and powerful of all the three great dōjutsu. Although a Kekkei Genkai like the Byakugan and Sharingan, it seems to be by far the most rarely occurring of the three, as there have been only two known Rinnegan users: the Sage of the Six Paths and currently, Nagato. It is so rare that Jiraiya thought its existence was only a legend. The Rinnegan is characterized by a ripple-like pattern around the pupil, with a grayish-purple background. In addition to enabling the user to quickly master various jutsu, the user may also use all forms of chakra nature manipulation, as well as the sixth "Yin-Yang" type of nature chakra about which little is known. Like the Sharingan and the Byakugan, the Rinnegan also allows the user to see chakra, including an otherwise hidden barrier.

Because the Six Paths of Pain are all reanimated corpses, their Rinnegan was added to their bodies by Nagato through some unknown means. By doing so, Nagato can see each individual body's field of vision, coordinating the bodies with extremely precise planning, especially during battles. Due to this effect, unlike the Byakugan, the Rinnegan does not have a blind spot, as long as the bodies are looking in every direction. Because of this advantage, an opponent must blind one body, or distract all others in order for a blind spot to be opened. The animals summoned by the Animal path also have Rinnegan eyes, suggesting that Nagato controls them as well.

Trivia

 * Rinne (輪廻) is the Japanese term for Samsara, the cycle of reincarnation or rebirth in several Indian religions. This is reflected in the names of Six Paths of Pain, which share the names with Samsaric realms of reincarnation.
 * Contrast to the anime depiction of it being multi-colored, the manga has shown that the Rinnengan actually is grayish purple in color. This mistake was most likely done due to the manga not releasing the color in time for the anime. This error was corrected as of episode 80 of Shippūden.