Rinnegan

The is the most revered and, according to Fukasaku, the most powerful of all the three great dōjutsu. The Rinnegan's occurrence is so rare that Jiraiya once believed its existence was only a legend, and Kakashi Hatake believes it to be only a mutation. There have thus far been only two known users: the Sage of the Six Paths and Nagato. With the Sage long deceased and with Nagato now dead, there are no confirmed Rinnegan users alive at this point.

Full Power Rinnegan
The Full power Rinnegan is characterized by a ripple-like pattern around the pupil, with a grayish-purple iris and sclera. In addition to enabling the user to quickly master various jutsu, the user may also use all forms of chakra nature manipulation which, as noted by Ibiki, literally allows its user to use any technique they wish. It also allows the user to use all of the six paths techniques. Like the Sharingan and the Byakugan, the Full Power Rinnegan also allows the user to see chakra, including otherwise hidden barriers. According to Nagato's partner Konan, the possessor of the Full Power Rinnegan is the seventh path of Pain, who is "beyond life and death", and can use the Outer Path: Samsara of Heavenly Life Technique, which allows the Full power Rinnegan user to revive all people who have died recently.

Because Nagato's Six Paths of Pain were all reanimated corpses, their Full Power Rinnegan was added to their bodies by Nagato through some unknown means. By doing so, Nagato could see each individual body's field of vision, coordinating the bodies with extremely precise planning, even during battles. Due to this effect, unlike the Byakugan, the Full Power Rinnegan does not have a blind spot, as long as the bodies are looking in every direction or at least one body is looking at the desired target. 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 had Full Power Rinnegan eyes, suggesting that Nagato controlled and could see through them as well.

Weaker Rinnegan
This is the Rinnegan that the Uchiha ancestor had.

Trivia

 * 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.