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
White Zetsu, along with several similar entities, were created using Hashirama's living clone, and the Demonic Statue of the Outer Path and as such, did not need to carry out human bodily functions. As Madara Uchiha's artificial creations, they served as his faithful underlings carrying out tasks he could not such as information gathering. White Zetsu along with a swirl-patterned clone were left to tend to Obito and help him in his rehabilitation. Over time, the duo became friends with the young Uchiha. At some point into Obito's rehabilitation was near completion, White Zetsu returned to the base alerting Obito to the fact that Kakashi and Rin were being attacked by Kirigakure shinobi. Resolved to save his friends, Obito tried to break a wall to get outside, but destroyed his artificial arm in the process. Seeing how desperate Obito was, the swirl-patterned Zetsu offered to help and encased himself around the young Uchiha in order to enable him to leave the cave.

Black Zetsu's origins currently remain unknown.

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 function as a single entity by communicating through their thoughts.

Zetsu is seemingly very trustworthy, being entrusted with knowledge of both Pain and Tobi's true identities, as well as the Eye of the Moon Plan, which his white half believes is beneficial to mankind. He has apparently been working with Tobi for some time, as Tobi first appeared as his "subordinate" and Zetsu later commented that Tobi's plans had been in the works for a long time. White Zetsu is also very confident in himself as he was willing to fight Naruto despite knowing that Pain had lost in battle against him. Zetsu has been described as having a love for money, at least by Hidan.

Zetsu (or at least White Zetsu) has been friends with Obito ever since he was saved by Madara in the Third Shinobi World War, something that appears to have transcended into his adulthood. When first meeting Obito, White Zetsu was playful and enjoyed teasing him about things, acting much like the goofy persona Obito would later take up. Although Obito was initially hostile towards him, the two befriended each other during the former's rehabilitation. White Zetsu also believes that Madara is a good guy at heart, as shown when he and the swirl-patterned Zetsu decided to help Obito without Madara's permission.

Zetsu's main role within Akatsuki is to function as a spy. As such, he 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. As such, he operated on his own, often moving between the different locations that the other Akatsuki members were located. This resulted in the members reporting directly to him, rather than the figurehead leader Pain. Zetsu would in turn report this directly to Pain as well as the actual leader, Tobi.

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, while the right side is 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. Under his Akatsuki cloak, Zetsu wears blue pants and sandals. He also has both legs wrapped in bandages, which hide the area where his black half's leg becomes white.

When the two halves split apart, the plant-like extensions also split and hang from the waists of both. Their clothes also split in half along with them, leaving each with one pant leg or half of an Akatsuki mantle, should they be wearing it. When they are emerging from the ground, these spike-like extensions surround the two halves in a circular pattern. The two have also demonstrated the ability to grow appendages to substitute for the missing half when split.

Unlike White Zetsu, who possesses a regular 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. In the anime, his fingernails are painted pink and his toenails, as seen at his début, are blue. He also wears his Akatsuki ring on his right little finger. In the manga however, Zetsu does not have fingernails. Some time after splitting, the two halves seemingly discarded their torn clothing.

Abilities
Zetsu, as a whole, has yet to be seen in battle. The technique he has been shown using the most is Mayfly, 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 is ideal for Zetsu's function as a spy, as it erases his presence as well, and is an ability that both halves, as well as White Zetsu's clones, can use. Although the two halves cannot converse through their thoughts while separated, they can extend roots underground which allow them to communicate with each other. It has also been noted that Zetsu, or at least his black half, has the ability to "record" the things he sees, as he has told Tobi that he recorded the battles between Sasuke and Itachi, and between Kisame and Killer B. He is also capable of showing these "recordings" to Tobi through unknown means. Black Zetsu is also a very powerful sensor, as he was able to sense Naruto Uzumaki and Killer B as soon as they touched the ground upon leaving the Island Turtle, which was some distance away. White Zetsu has not demonstrated any sensory ability.

Zetsu is able to split in two, which allows his two halves to act independently. White Zetsu has mainly been seen using support abilities and Tobi has referred to him as not being a "front line" fighter. With his Spore Technique, White Zetsu is able to plant spores on the bodies of others, which are undetectable even to sensors and Kage-level shinobi. Once activated, these spores grow into a mushy mass around the individuals they formed on by sucking out their chakra and restrict them. The spores can also use this stolen chakra to replenish an ally's chakra supply by attaching themselves to him or her. In addition, White Zetsu is able to create and control near-identical copies of himself, which can be used as a special substitute by taking on the appearance and unique chakra of anyone White Zetsu touches. The clones are much weaker than the original and are therefore mainly used as decoys.

Nature Transformation
Due to possession of 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 for offensive purposes 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. Later his silhouette appeared with the rest of the Akatsuki members where they discussed Orochimaru taking Sasuke Uchiha, the capturing of the Nine-Tails and the furthering of their plans.

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. Zetsu is later seen sealing the Two-Tails.

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 Tobi to where Itachi and Sasuke were.

Tsuchigumo Kinjutsu Arc
During this arc, Zetsu was present alongside the other Akatsuki members when they extracted the Six-Tails from Utakata.

Invasion of Pain Arc
After the battle between the Uchiha brothers, Tobi met with Zetsu on a bridge where they discussed the fact that Itachi — who had been hampering their plans — was dead and Zetsu enquired what Tobi's next move would be.

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 slip away from Taka unnoticed. At that time, Black Zetsu was in the Land of Iron with Tobi, who instructed him to "begin". White Zetsu then emerged in the conference room, telling the five Kage that Sasuke was somewhere around. After revealing himself, the Fourth Raikage grabbed the white Zetsu's neck, asked him about the whereabouts of Sasuke, and threatened to use force. Zetsu mockingly replied that he would give a hint, which prompted the Raikage, angered, to tighten his grip on Zetsu's neck. With his neck snapped, the White Zetsu collapsed on the floor and was presumed to be dead by everyone in the vicinity.

After Sasuke had been struck by the Fifth Mizukage's Boil Release: Skilled Mist Technique, Zetsu's Spore Technique, which had secretly been implanted on everyone in the meeting hall before the Raikage's attack, activated. The spores leached some of the Mizukage's chakra while binding the samurai guards, Mifune, Ōnoki and everyone else. Black Zetsu commented on how foolish the five Kage were, as they had failed to detect his technique. One of the spores then jumped onto Sasuke and gave him the absorbed chakra, allowing him to use an arm of Susanoo to escape from the Mizukage. The spores were later successfully neutralised by everyone present at the time of their release.

After Naruto and Sasuke clash, the aftermath of which sends Sasuke hurtling towards a wall, a clone of White Zetsu appears and wraps himself around Sasuke to cushion 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 more 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 rejoining 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 White Zetsu's 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 that 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 one 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 to enact Tobi's plan to capture the daimyō and hold them hostage to force the opposition to bring Naruto and Killer B to them. White Zetsu, on the other hand, is left behind to make sure Kabuto could not abduct Sasuke during the confusion of war. Later, after Kabuto demonstrates the Summoning: Impure World Reincarnation 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 with their quarry now in the open, Black Zetsu was ordered to continue with his guerilla tactics against the Mizukage's team to keep them from regrouping with the rest of their forces. The fight continued throughout the night. During Black Zetsu's fight on the second day of the war, White Zetsu ends up being used as a test subject for Sasuke's new eyes, impaled by the youth's Susanoo before being 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. Immobilised, Black Zetsu wondered how the sword grew to such a size in an instant, he is then pinned to the ground by Chōjūrō's blade as the Mizukage departed.

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 databook(s):
 * 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.
 * Zetsu and the White Zetsu Army clones are not dissimilar to the legends told of the mandrake plant used to create artificial men.
 * Zetsu is the only member of Akatsuki that has yet to make a playable appearance in any game.

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."
 * 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!"