Mangekyō Sharingan

The is a heightened form of Sharingan. The Mangekyo Sharingan gives the user access to powerful and forbidden techniques. The Mangekyo Sharingan is distinguished from a normal Sharingan through its appearance, which changes the form of the tomoe seal. Unlike in the case of the Sharingan, the appearance of the Mangekyo Sharingan differs from user to user; Kakashi Hatake's and Itachi Uchiha's both resemble pinwheels, Madara Uchiha's and his brother, Izuna's look more like a detailed form of the basic three-tomoe Sharingan, and Sasuke Uchiha's looks like a star.

To acquire the Mangekyo Sharingan, someone close to a Sharingan user must die and the emotion of the loss is responsible for its unlocking. To expedite this occurrence, most Uchiha throughout history have killed their closest friends or family members in order to meet this criteria, though, how Kakashi gained his Mangekyo Sharingan has yet to be explained. (It is interesting to note that in order to obtain the Mangekyo Sharingan, one must feel the emotion of losing a friend, the act of killing them or watching them die alone will not activate it. This is seen with Sasuke and his Mangekyo.)

Over time, use of the Mangekyo Sharingan deteriorates the user's eyesight to the point of blindness. Only by taking and transplanting the eyes of one's sibling (who also wields the Mangekyo Sharingan) can the vision be restored, a process that results in the creation of the. Not only does this process restore one's eyesight, but it also gives the person greater power. There are only three known living shinobi left who possess the Mangekyo Sharingan: Kakashi Hatake, Madara Uchiha, and Sasuke Uchiha.

Itachi Uchiha
Itachi Uchiha gained the Mangekyo Sharingan by killing his best friend, Shisui. With the Mangekyo Sharingan, Itachi was able to use at least three (and the most, as of yet) of the most powerful jutsu. The first was Tsukuyomi, an extremely powerful genjutsu that allowed him to torture opponents for what seemed like days in a matter of moments. The second technique was Amaterasu, a substantially potent ninjutsu, which creates virtually-inextinguishable black flames at the user's focal point that continue to burn until the target is reduced to ash. The last of these techniques was Susanoo, which allowed Itachi to summon a massive ethereal warrior. This entity fights on behalf of Itachi and shields him from all attacks, rendering Itachi essentially invincible.

All of these techniques use massive amounts of Itachi's chakra and, in addition to damaging his eyesight, put a great deal of strain in his body. During his final battle against Sasuke, Itachi's eyes were even shown bleeding after using the Mangekyo. He also told his brother that he wanted to take his eyes so that he can restore his eyesight and gain more power. During the resulting battle, Zetsu noted that Itachi's "Left Mangekyo" possessed the Tsukuyomi, while the "Right Mangekyo" possessed the Amaterasu.

Kakashi Hatake
Kakashi Hatake developed his own Mangekyo Sharingan during the time-skip. With his Mangekyo Sharingan, Kakashi mastered a technique that creates a localized inter-dimensional space-time ninjutsu called Kamui, allowing him to target any person and/or object and send it to another dimension. The attack requires considerable effort to aim precisely and appeared to leave Kakashi's chakra significantly drained; He collapses after using the technique three times even at full strength in a single day. How he awakened his Mangekyo Sharingan remains unknown, as he stated that everyone close to him was dead.

Madara Uchiha
Madara Uchiha is the first Uchiha to gain the Mangekyo Sharingan. His Mangekyo took the form of a ring with three circular holes in it. He eventually grew blind from overusing it, and only by taking his younger brother Izuna's eyes did he regain his sight. This also gave him an "Eternal" Mangekyo Sharingan that gave him great power. His Eternal Mangekyo Sharingan looks identical in appearance to Madara's first Mangekyo combined with Izuna's Mangekyo.

Madara, posing as Tobi, has shown using an unnamed space/time ninjutsu which makes him nearly invulnerable and allows him to teleport to different places at will very quickly, but it's unclear if this is a result of his Mangekyo Sharingan. He may likely also be able to put out the so-called inextinguishable flames of Amaterasu quite easily.

In the past, Madara was able to use his Mangekyo Sharingan to control the Nine-Tailed Demon Fox like a pet. However, it has yet to be shown in the present.

Izuna Uchiha
Izuna Uchiha acquired his Mangekyo Sharingan soon after Madara did. His took the appearance of three bars stretching out of his pupil. Madara later took Izuna's eyes to regain his lost vision. In Madara's story, however, Izuna volunteered to give him his eyes for the clan's sake.