Zetsu

is a member of Akatsuki and one of Tobi's most loyal subordinates. The black half is known as, while the white half was known as.

Background
After obtaining the cells of Hashirama Senju, TobiNeed source used them to cultivate an alter ego for Black Zetsu, thus creating the white half that would be known as "White Zetsu".

Personality
Accordingly with his two differently coloured halves, Zetsu has a split personality. In the Japanese version of the manga, Black Zetsu only uses katakana for okurigana and furigana while White Zetsu uses kanji and kana regularly. This is often conveyed in the anime through the use of different voice actors. The two halves also converse with each other, and occasionally differ in opinion (Black Zetsu is more serious and knowledgeable while White Zetsu is carefree and easygoing). Despite these individualities, they are still able to communicate through their thoughts and function as a single entity.

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. White Zetsu is also 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 is able to control 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 to 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 report 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 with small white dots along his body. 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 White Zetsu, which shows a normal mouth, nose, and eye, Black Zetsu shows no visible orifices at all and only his iris is visible. Black Zetsu 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 début, are blue. He also wears his Akatsuki ring on the right little finger. In the manga however, Zetsu does not have fingernails. Black Zetsu 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 quickly travel to a new location, though he isn't as fast as Tobi'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 Tobi that he had recorded the whole battle between Sasuke and Itachi, and between Kisame and Killer B but 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 B as soon as they left the Island Turtle which was some distance away.

Zetsu can also split in two, so that his two personalities can act independently. Tobi refers to the White Zetsu as not being a "front line" fighter, and White Zetsu has mainly been seen using support abilities. White Zetsu is able to use a time-delayed Spore Technique 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. Furthermore, White Zetsu is able to create multiple copies of himself as well as a special clone which can simulate the appearance anyone Zetsu has ever touched right down to their chakra, stating it was a mix of the original person's chakra and the Transformation Technique. These clones however, are much weaker than the original, and therefore mostly useful as decoys.

Nature Transformation
Due to being created from Hashirama Senju's cells, Zetsu is capable of using the former's Wood Release, albeit on a much weaker scale. This has been most prominently demonstrated through Black Zetsu, who has been depicted transforming parts of his body into roots to converse with White Zetsu for near instantaneous communication, as well as freely manipulating them during battle.

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, finding Mukade a delicious meal.

After Sasori and Deidara are defeated, Zetsu is sent, along with Tobi, to retrieve their rings and eat their corpses. However, he is unable to eat Sasori due to him being a puppet, but is amazed to finally see what Sasori looks like. Tobi finds Sasori's ring, wishing to take his place. Black Zetsu thinks this is a bad idea, but White Zetsu thinks it will be a good one. They later find Deidara's severed right arm and believe him dead until he arrives and proves them wrong. Black Zetsu wonders why Deidara hasn't captured Naruto Uzumaki, but Deidara tells him that he fulfilled his quota.

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
Zetsu was seen to reveal himself right after Pain's fight with Jiraiya. 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 Tobi of the result of the fight and was called "aloe vera" by Naruto. White Zetsu took some offence to the name while Black Zetsu 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 Tobi's ongoing plans as now there were 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 White Zetsu proceeded to lead Sasuke and his team to the Kage Summit while Black Zetsu remained behind and discussed with Tobi 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. Tobi declared that he was tired of hiding, and explained that they needed to speed up the "Eye of the Moon Plan".

White Zetsu stayed with Taka 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, White Zetsu managed to leave Taka and slip into the conference room, telling the five Kage that Sasuke was somewhere around. At that time Black Zetsu was with Tobi, 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 who 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 activated his Spore Technique, which was secretly implanted on 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. Black Zetsu comments on how foolish the five Kage were, as they failed to detect his technique. 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. The clones are later successfully neutralised by everyone that was at the summit.

After Naruto and Sasuke clash, the aftermath of which sends Sasuke hurtling towards a wall, a clone of White Zetsu appears and cushions the blow. Revealing that Tobi had told him to keep an eye on Sasuke, the clone contacts the real White Zetsu who alerts Tobi. Upon Tobi's arrival, the White Zetsu clone, prepared to fight and capture Naruto created several copies of himself. Before he could engage in combat however, Tobi 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 Black Zetsu.

White Zetsu and Black Zetsu meet up at the site of Killer B and Kisame's battle only to reveal that Kisame's decapitated body was actually one of their shape-shifting clones. It is then revealed that Kisame, by having the clone fake his death, was then able to infiltrate Kumogakure while inside Samehada which was being carried back to Kumogakure by Killer B who intended to use it as his own weapon. Black Zetsu then stated that it was their feeding time and they should merge once again.

Confining the Jinchūriki Arc
Upon Tobi'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.

Tobi promised to give him "one Zetsu" if Kabuto captured the Nine-Tails. Later, Tobi revealed his army comprised of hundred thousand clones of white Zetsu to Kabuto, which he would use to fight the numbers of the Allied Shinobi Forces.

Shinobi World War Arc
Supervising Sasuke's recovery, Zetsu tells him to be patient when asked if his bandages could be removed, remarking that when he does regain his sight it would be to a different world as things had got "amusing". As the Fourth Shinobi World War commences, Black Zetsu departs, leaving White Zetsu behind to attend to Sasuke, to prevent Kabuto from abducting with him during the confusion of war. Later, after Kabuto demonstrates the Summoning: Impure World Resurrection technique, Black Zetsu arrives beside Tobi and confirms that White Zetsu's spores had attached themselves to the former, before being instructed to carry out his assigned tasks.

Emerging from the ground near the daimyō's hideout, Black Zetsu infiltrates the structure, despite alerting the enemy to his presence. However, upon discovering the daimyō's absence, Black Zetsu retreats and declares that they shouldn't underestimate his capabilities, as he was a part of the very land itself. Later locating his desired targets, he is instead obstructed by Mei Terumī and her squad, but sensing the Eight and Nine-Tails' chakra while confronting the team, he immediately communicates this to Tobi via White Zetsu. Told that the daimyō were no longer necessary, since the jinchūriki were out in the open, Black Zetsu is ordered to continue with his guerilla tactics against the Mizukage's team regardless, so as to keep their forces divided.

At headquarters the following day, Sasuke tests out his new eyes, conjuring up the new form of his Susanoo and impaling White Zetsu upon its blade, who is then incinerated by the flames of Amaterasu.

Continuing to battle with Mei and her squad, Black Zetsu observes the arrival of Naruto's shadow clone to their location, who soon proceeds to crash into a tree beside him. Growing roots from portions of his body whilst fighting, he uses them to trip Naruto and avoid his Rasenshuriken, only to be bisected from behind by the enlarged blade of Chōjūrō's Hiramekarei. Unable to neither move nor comprehend how the sword grew to such a size in an instant, Black Zetsu is then pinned to the ground by Chōjūrō's blade.

Creation and Conception
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 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 "Tobi" is, Zetsu is never far behind.
 * Although most characters call Tobi "Madara Uchiha", Zetsu still refers to him as "Tobi".
 * Tobi 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 Zetsu: "Idiot, it's not that simple." White Zetsu: "It'll be all right, after all, Tobi is a good boy."
 * (To Hidan) White Zetsu: "Sorrow begets solitude…" Black Zetsu: "…the only thing you can have faith in is yourself."
 * (When Killer B's body turned into a tentacle during extraction) White Zetsu: "Ahahaha a tentacle!" Black Zetsu: "It's not funny!"
 * (After Naruto called him Aloe vera) White Zetsu: " 'Aloe vera'?!" Black side: "Just ignore him…"
 * Black Zetsu: "An expert with a pebble can still beat a novice with a shuriken."
 * Black Zetsu: "I can't believe no one noticed my Spore Technique… The Five Kage are a bunch of fools!"
 * Black Zetsu: "They underestimate Black Zetsu's powers… I am the land itself!"