Zetsu

is a member of Akatsuki and is one of Madara Uchiha's most loyal subordinates. He acts as the organisation's spy and is the main source for Madara's army for the Fourth Shinobi World War.

Personality
According with his two differently coloured halves, Zetsu seems to have a split personality, as in the Japanese version of the manga, the black half of his face only uses katakana for okurigana and furigana while the white side uses kanji and kana regularly. The two halves also converse with each other, and occasionally differ in opinion (the black half is more serious and intelligent while the white half is carefree and easygoing). Despite these individualities, they are able to communicate through their thoughts.

Zetsu is seemingly very trustworthy, being entrusted with knowledge of Pain and Tobi's true identities. He has apparently been working with the latter for some time, Tobi first appearing as his "subordinate" and Zetsu later commenting that Tobi's plans had been in the works for a long time. The character showed some lust for money when he quoted Kakuzu on his principle that money is most important. However, whether or not this applies for both personalities is as of yet a mystery to be dealt with. Zetsu's white side has also shown to be very confident in himself as he was willing to fight Naruto despite knowing Pain had lost in battle against him.

Zetsu's main role within the Akatsuki is to function as a spy, and often performs duties that are similar to a hunter-nin. He has been shown able to move his body and take part in the tailed beasts sealing ritual simultaneously which, in addition to being unique to him, allows him to act as a lookout while the sealing takes place. When an agent to Akatsuki, or possibly even a member, dies, Zetsu is sent to devour their bodies so as to not have their secrets revealed, which adds further his venus fly trap theme. Zetsu is also the one sent to retrieve the rings of dead Akatsuki members. Due to the role he plays, Zetsu is the only member of Akatsuki to act without a partner on a regular basis. Despite this, Zetsu serves as a sort of superior to other members, as they often reported directly to him instead of to the actual leader, Pain.

Appearance
Zetsu is easily distinguished by two large venus fly-trap like extensions that envelop his head and upper body, giving him a plant-like appearance. When his extensions are open and his head is visible, it is revealed that Zetsu has short green hair, yellow eyes, and that his body has two different coloured halves. His left side is completely white and the right side black. The black colour doesn't extend all the way down Zetsu's body, as his feet are both white. When he splits into two the plant-like extensions go down the waist and now have the appearance of spikes, each halve has half of the Akatsuki robe and the missing half is replaced with new body mass.

Unlike the white side, which shows a normal mouth, nose, and eye, the black side shows no visible orifices at all and only shows the iris of the eye. The black half also has white dots along the edges of his body where the two halves meet; these are not flat markings, but rather protrude from his body, like little white bumps. Zetsu also has unusually rounded teeth. His fingernails are painted pink and his toenails, as seen at his debut, are blue. He also wears his Akatsuki ring on the right little finger. In the manga however, Zetsu does not have fingernails. Zetsu's black half is also seen wearing standard shinobi sandals and pants, along with bandages on his ankle.

Abilities
Zetsu as a whole has yet to be seen in battle. The technique he has been shown using the most is his Mayfly technique, with which he merges with the ground to instantly travel to a new location, though he isn't as fast as Madara's own space–time travelling. This technique makes it ideal for Zetsu's function as a spy, as it erases his presence as well, and is an ability both his halves can use. Zetsu can also use it to extend roots underground through which he can communicate with his other half should they be separated. It has also been noted that Zetsu has the ability to "record" the things he sees, as noted when he tells Madara Uchiha that he had recorded the whole battle between Sasuke and Itachi, and between Kisame and Killer Bee. It is unknown how he is able to show these "recordings". He is also a very powerful sensor, able to sense Naruto Uzumaki and Killer Bee leaving the Island Turtle.

Zetsu has also shown the ability to split in two, so that his two personalities can act independently. Madara refers to the White Zetsu as not being a "front line" fighter, and White Zetsu has mainly been seen using support abilities. The White side is able to use a time-delayed spore jutsu to grow into a mushy mass around several individuals at once, thereby sucking their chakra out, and can even use it to replenish another persons' chakra. White Zetsu has shown the ability to create multiple copies of himself. White Zetsu can create a special clone which can simulate the appearance anyone Zetsu has ever touched down to their chakra. These clones however, are much weaker than the original person, and therefore mostly only useful as a decoy.

Sasuke Retrieval Arc
After Sasuke and Naruto's fight at the Valley of the End, Kakashi and Pakkun appear to bring Naruto back home. As the three begin the journey back home to Konoha, Zetsu appears from the ground, having witnessed the whole battle.

Part II
Zetsu appears frequently throughout the series. In addition to serving his various Akatsuki duties, he watches battles of interest and then reports the outcome to the other members, and eats the bodies of dead associates.

Kazekage Rescue Arc
During the extraction of the One-Tailed Shukaku, Zetsu is seen also spying on Team Guy and Team Kakashi and alerting Akatsuki. Later, he is sent to dispose the corpses of Mukade and Yura. Zetsu is present with Tobi when retrieving Sasori's ring and when locating Deidara.

Hidan and Kakuzu Arc
After Hidan and Kakuzu defeated Yugito Nii, Zetsu appeared to retrieve Yugito to start the extraction. When Hidan claimed that Akatsuki was just after money like Kakuzu, Zetsu told him that when he's sad and alone, all you can count on is yourself.

Itachi Pursuit Arc
During the fight between Sasuke and Itachi, Zetsu watched and recorded the entire battle. When Itachi died Zetsu noted that there was something different in Itachi's fighting style during the battle. He later appeared to inform Madara of the result of the fight and was called "aloe vera" by Naruto. The white half of Zetsu took some offense to the name while the black half told him to ignore him. He then led him to where Itachi and Sasuke were.

Five Kage Summit Arc
After Itachi's defeat and Sasuke's recruitment, Zetsu took a more active role in Madara's ongoing plans as now there are only three Akatsuki members left, marvelling at the effort that went into getting Sasuke to work with Akatsuki. He was later revealed to have watched the entire fight between Pain and Naruto Uzumaki, and appeared next to Tobi as he argued with Sasuke about what his next objective was. There he revealed that Konoha had already been destroyed. When asked by Tobi, he revealed that Danzō had been named the acting Sixth Hokage. He then proceeded to explain the outcome of the battle between Pain and Naruto. When Taka agreed to go to the Kage Summit, Zetsu revealed his ability to split in half, and the white half proceeded to lead Sasuke and his team to the Kage Summit while the black half remained behind and discussed with Madara the fact that they might lose control over Sasuke and would therefore lose their last chance to have someone sync with the Demonic Statue of the Outer Path. Madara declared that he was tired of hiding, and explained that they need to speed up the "Eye of the Moon Plan".

The white half stayed with Taka, currently in the Land of Iron, observing the meeting of the Five Kage and trying to figure out a way to successfully assassinate Danzō. After identifying Danzō, the white half managed to leave Taka and slip into the conference room, telling the five Kage that Sasuke was somewhere around. At that time the black half was with Madara, both hidden in the Land of Iron and received the instruction to "begin". After revealing himself, the Fourth Raikage grabbed the white Zetsu's neck, asking him the whereabouts of Sasuke, and threatened to use force. Zetsu mockingly replied that he would give a hint. The Raikage, angered, tightened his grip on Zetsu's neck. White Zetsu collapsed on the floor, and everyone there presumed that he died.

After Sasuke had been struck by the Fifth Mizukage's Boil Release: Skilled Mist Technique, Zetsu used some kind of Spore Technique, which was secretly implanted in everyone in the meeting hall before the Raikage's attack. The spores leached some of the Mizukage's chakra while binding the samurai guards, Mifune, Ōnoki and everyone else. His black half comments on the five Kage being fools, as they failed to detect his spore jutsu. One of the spores then jumped onto Sasuke, but instead gave him the absorbed chakra, allowing him to use an arm of Susanoo to escape from the Mizukage. Everybody is able to remove the spore technique thanks to Kankurō's puppet strings, with the exception of the Five Kage and Akatsuchi (they removed it themselves). Mifune then stabs one of Zetsu's clones through the head. The spores had also been implanted within Kurotsuchi, Ao, Danzō, Fū, and Torune, all of whom had left the meeting hall for various reasons, but they had managed to get the parasitic technique off of themselves.

Zetsu's white half reveals after Sasuke and Naruto clash that Madara told him to keep an eye on Sasuke. Upon calling Madara back, white Zetsu was prepared to fight and capture Naruto while he demonstrated an ability to create several copies of his white half. Before he could engage in combat however Madara tells him not to as he wasn't a 'front line' fighter, and instead gives him the task of checking up on Kisame and to rejoin with his black half.

White Zetsu and his Black half met up at the site of Killer Bee and Kisame's battle only to reveal that Kisame's decapitated body was actually one of their shape-shifting clones. The real Kisame, by having the clone fake his death, was then able to infiltrate Kumogakure while inside his sword, Samehada. The sword itself is being carried on the back of Killer Bee who plans to use it as his new weapon. Black Zetsu then says that it's their feeding time and they should rejoin.

Confining the Jinchūriki Arc
Upon Madara's return to the base, Zetsu, now with his halves rejoined, informs him that the scroll with information from Kisame Hoshigaki sent through his messenger shark had arrived. He also noted that everything seemed to be going in their favour. Kabuto mentioned he could make Zetsu stronger and that he was the key to fighting the shinobi forces. Madara promised to give him "one Zetsu" if Kabuto captures the Nine-Tails. Later, Madara revealed to Kabuto a hundred thousand clones of white Zetsu, which will be used to match the numbers of the Allied Shinobi Forces.

Shinobi World War Arc
The original Zetsu was left at the headquarters to keep an eye on Sasuke while he's recovering in order to prevent Kabuto from capturing him during the war. He tells Sasuke to be patient when Sasuke asks whether or not it was time to remove his bandages and that when he does he would see a different world; stating that things have gotten fun. Later Zetsu's black half arrives near Madara who inquires if White Zetsu's spores have already attached themselves to Kabuto. When Black Zetsu affirms this Madara then instructs him to carry on with his own assigned tasks.

Later, Zetsu's black half emerges from the ground at the daimyō's guarded safe house. His attempt to capture the daimyo's was intercepted by Mei Terumī, who revealed that he must defeat her whole team to get past. After sensing the chakra of the Eight and Nine-Tails' hosts he sends a message to his white half who alerts Madara. Madara replied he didn't need the daimyō anymore since the jinchūriki were out in the open. He however told Zetsu to continue the attack of the Mizukage's team to keep the forces divided.

Creation
In Naruto Hiden: Sha no Sho Character Official Data Book, Kishimoto revealed that he had originally planned for Akatsuki to be a group of monsters, "with almost no human characteristics", and that Zetsu's design was modelled after an insectivorous plant. He also stated that he had decided to make Zetsu half black and half white to "better show his split personality".

Trivia

 * According to Zetsu's card in the Naruto Shippūden card game, he is from Konoha.
 * Kishimoto first intended to make Akatsuki's members monsters with almost no human traits. Zetsu is a prime example of this.
 * According to the Third Databook:
 * Zetsu's hobby is observing unique shinobi.
 * Zetsu wishes to fight people who are likely to leave behind a corpse that will make a good meal.
 * Zetsu's favourite food is chewy people, while his least favourites are konnyaku and jelly.
 * Zetsu's favourite phrase is, which roughly means "The only one you can count on is yourself".
 * Wherever Madara is, Zetsu is never far behind.
 * Zetsu still refers to Madara Uchiha as Tobi.
 * Madara made a deal with Kabuto, in that he would give him "one Zetsu", provided he were to capture the Nine-Tails. The specifics of this deal have yet to be elaborated on.

Quotes

 * (To Tobi about joining Akatsuki) Black side: "Idiot, it's not that simple." White side: "It'll be all right. Tobi is a good boy."
 * (To Hidan) White side: "Sorrow begets solitude ..." Black side: "... the only thing you can have faith in is yourself."
 * (When Killer Bee's body turned into a tentacle during extraction) White side: "Ahahaha a tentacle!" Black side: "It's not funny!"
 * (After Naruto called him Aloe vera) White side: " 'Aloe vera'?!" Black side: "Just ignore him..."
 * Black side: "An expert with a pebble can still beat a novice with a shuriken".
 * Black side: "The Five Kage are a bunch of fools!"
 * Black side: "They underestimate Black Zetsu's powers...I am the land itself!"