rinnegan
The Rinnegan, as depicted in Naruto, is reputed as the most exalted eyes amongst the Three Great Dōjutsu, the others being the Byakugan and the Sharingan. They are characterised by light purple or red sclerae and irides with a ripple-pattern that spreads over the eyeball that are sometimes marked with tomoe.
Both of Uchiha Madara's eyes eventually become this. Upon his impending death, his eyes are transplanted into a young Nagato, who later exposes them via the use of the Six Paths of Pain. After Nagato's demise and his unmasking, Uchiha Obito's left eye socket is shown to have one of Madara's original Rinnegan implanted in it, and Uchiha Sasuke's Eternal Mangekyou Sharingan is evolved into a powered up Rinnegan as he is visited by the Sage of the Six Paths while in near death.