- "This world will become one. I have found the way. Race, tribal affiliations, national borders... even our faces will be irrelevant. The world that The Boss envisioned will finally become a reality, and it will make mankind whole again."
Zero (real name David Oh, and formerly known as O, Major Tom, Major Zero and Cipher) was the original commander of CIA Special Forces Unit FOX (Force Operation X). After Zero became a founding member of the Patriots along with Big Boss, the two friends would later develop a bitter enmity.
Early life and career
Prior to creating FOX, David Oh served in Layforce with The Boss, participating in various raids in Egypt. They were close friends with a fellow member of Layforce who died on December 30, 1941, with Oh personally delivering his winged dagger pin to The Boss. He and The Boss also served in the British SAS. Oh later met and recruited the Hungarian assassin Skull Face into the SAS after the latter defected from the Soviet Union. Impressed with his skills as an assassin and military tactician, Oh quickly promoted Skull Face to be his Executive Officer. During his later career in MI6, he was referred to as "O." Oh ultimately joined the CIA, under the bureau of classified planning, where he gained the codename "Zero" (derived from "O").
In September 1962, Zero helped Dr. Nikolai Sokolov and his family defect from the Soviet Union to America, but was forced to allow Sokolov himself to be taken back due to a secret deal made between the two superpowers during the Cuban Missile Crisis. After reuniting with The Boss, the two formed the CIA's FOX Unit much to the DCI's dismay. However, Zero's own reasons for forming FOX was to prepare himself for a second attempt at recovering Sokolov.
While serving in the CIA, Zero recruited Donald Anderson and Dr. Clark into the organization as he recognized their potential, though he ended up receiving complaints three days per month relating to Anderson. Zero also formed a club within the CIA dedicated to finding UMAs, and acted as its president, with Sigint as its vice president. At some point, he also took in an orphan, gave her food and a place to live. Prior to 1964, Zero obtained a residence in Portsmouth, New Hampshire.
He later promoted Skull Face to be the commander of the XOF, a covert support unit Zero had secretly created as an insurance policy for the success of the newly formed FOX. Members of the unit were tasked with providing tactical support and field intel to FOX operatives in a covert manner. Its overall purpose was to ensure the survival of FOX operatives during missions. Any information regarding the XOF and their activities was highly classified to the point where even The Boss herself and the CIA were unaware of their existence. Unbeknownst to Zero at the time, however, Skull Face harbored a deep-seated hatred for both him and Jack.
By August 1964, Major Zero served as FOX's commanding officer for the Virtuous Mission, the objective being to once again rescue Sokolov in Tselinoyarsk, USSR. Earlier, Zero briefed his friend Jack on the previous attempt to rescue Sokolov, explaining that the Soviets most likely wanted him to finish a weapons system he had begun developing, capable of turning the tide of the Cold War. He also warned Jack that if he didn't retrieve Sokolov in four hours, then they wouldn't have enough time to extract the two from Tselinoyarsk. Zero gave Jack the codename Naked Snake due to the on-site procurement and stealth aspects of the mission, and designated himself as "Major Tom" due to incorrectly remembering the successful escape tunnel's name in The Great Escape.
To ensure that the mission was a success, Major Zero had secretly deployed a covert XOF team led by Skull Face to monitor Snake's progress during the mission, although they were ordered to stay out of sight and not interfere with Snake's mission in any way. Upon Snake's arrival at Rassvet, Major Zero explained to him that he needed to deliver Sokolov a message when he rescued him: "Sorry for being so late." Upon learning of the dangerous circumstances between the KGB and the GRU's current rivalry, he also insisted that Snake get out of there with Sokolov quickly.
Following the Virtuous Mission's failure, Zero was shocked by The Boss's defection to the Soviet Union and Sokolov's facility's bombing as he viewed her with higher regard than even his own family, although he did later admit that she had an aura of mystery surrounding her. He also felt that his new codename might have been a mistake so he re-watched the film roll for The Great Escape, having arranged its delivery through the film company, and thus realized his error. Zero later visited Snake in an advanced ICU, offering him a Cuban cigar. There he explained to Snake that the Government was willing to revoke the charges in regards to any and all involvement in The Boss's defection, under the condition that he accepts the follow up mission Operation Snake Eater. Zero also implied during this visit that he had been placed in the same situation as Snake, and that if he failed the mission, then not only would FOX be disqualified from becoming an official unit, but he and Snake may also be executed.
Major Zero again served as Snake's commanding officer during Operation Snake Eater, with Para-Medic (Dr. Clark) and Sigint (Donald Anderson) providing radio support, the supposed KGB spy EVA assisting Snake with transportation. In addition, a covert XOF team led by Skull Face was again sent to Tselinoyarsk to provide covert support to Naked Snake.
When it appeared that Sokolov was committing adultery on his wife and child with Tatyana (in reality, she was Volgin's lover), Zero was in disbelief and tried to point out how he wasn't the kind of person to do so before Snake told him that "people change." In addition, when investigating Sokolov's supposed lover's identity, he initially speculated that her being a supposed KGB officer was obscure within the ranks of the KGB when he couldn't get any leads. After Sokolov was apparently killed by Colonel Volgin, Zero decided to make the Shagohod's destruction a top priority to honor his fallen friend. He later learned from Snake about his communicating with The Sorrow. But despite insisting that he'll believe whatever Snake had to say, he spoke to Para-Medic and voiced that he may have gone insane before Snake pointed out that he could still hear them. The mission was a success as the Cobra Unit were killed off, the Shagohod weapon was destroyed, and both Volgin and The Boss were defeated.
After Naked Snake was awarded the "Big Boss" codename by the President, Zero congratulated Snake but his friend was too distraught to say anything to him and eventually left FOX and America to drift around nations as a mercenary.
At some point, he became involved in a secret plan known as "the cleanser project" which seemingly involved using biological agents (such as the vocal cord parasite) to target an entire race of humans for unknown reasons. This plan was later resurrected by Skull Face for his own destructive goals.
- Main article: San Hieronymo Incident
|Warning: The following information is from outside Hideo Kojima's core "Metal Gear Saga." It has some level of canonicity within the continuity, but reader discretion is advised.[?]|
In November 1970, Major Zero was arrested for treason after being accused of instigating the FOX rebellion on the San Hieronymo Peninsula. Having come under suspicion himself, Big Boss set out to clear his and Zero's names, with radio support from Para-Medic and Sigint via a radio frequency that Zero had maintained for such an emergency.
Zero had conspired with the CIA triple spy Ocelot to bring about the incident, in order to obtain the remainder of the Philosophers' Legacy. They wished to use the Legacy to end the Philosophers' power and reform the organization, after having observed its American branch further degenerate into squabbling factions. Using Ocelot, Zero manipulated the charismatic Gene into staging the rebellion and stealing the CIA's new Metal Gear, forcing the CIA Director into a vulnerable position with the threat of a nuclear launch. While Ocelot was initially unaware of his co-conspirator's identity, Gene had his suspicions, referring to "the man with the same codename as Null."
Neither Zero nor Ocelot had anticipated that Gene would actually launch Metal Gear into America, thus framing the Soviet Union and ending the current détente in the Cold War. However, Big Boss and Roy Campbell were able to form a resistance movement on the peninsula, and ultimately foiled the launch attempt. Meanwhile, having supplied Metal Gear's trajectory data to the DCI, Zero had Ocelot assassinate the Director as he attempted to take shelter in a secret bunker beneath the CIA headquarters. Ocelot then stole the documents that the DCI had intended to save from destruction, regarding both the Philosophers' Legacy and a list of the organization's members, and provided these to Zero.
After they were cleared of all charges, Major Zero, Para-Medic, Sigint and a senior Government official greeted Big Boss at a runway upon his return to America by plane. There Zero handed him documents that would allow for the creation of a new special forces unit, following his disbandment of FOX.
Zero later shared with Ocelot the battle data on the Perfect Soldier Project and gave hints about genomes as bargaining chips to which Ocelot agreed to stay working together under the condition that they recruit Big Boss into their new organization: The Patriots.
|Non-"Metal Gear Saga" information ends here.|
Creation of the Patriots
Les Enfants Terribles
Zero recruited Big Boss, Sigint, Para-Medic, Ocelot, and EVA to form the Patriots. Using the Philosophers' Legacy as a limitless source of funding, Zero hoped to carry out what he believed to be The Boss's vision by turning Big Boss into a charismatic icon and unifying the world by controlling information. Zero's stature rose and his influence grew inside the halls of Langley. But when Big Boss started to disagree with the goal, Zero feared that his friend might leave the organization so he had Dr. Clark (Para-Medic) create clones of Big Boss in order to maintain the Patriots' icon in a project known as Les Enfants Terribles. When Big Boss found out about the project, he condemned it and, considering this to be the last straw, parted ways with Zero and left the United States to form his own private military company. EVA also left the Patriots out of loyalty to Big Boss. Ocelot stayed with the organization but maintained limited contact.
After falling out with Big Boss, Zero went into hiding. Because of this instance, he also did not personally assign missions to his agents, instead using proxies to relay orders. Only one exception existed: his operative Pacifica Ocean, whom he personally met at his hiding spot in Hell's Kitchen, Manhattan to have her make contact with Big Boss.
- Main article: Peace Walker Incident
In 1974, the Patriots, now known as Cipher, orchestrated the Peace Walker Incident in Costa Rica involving Hot Coldman's AI weapons. To carry this out, Cipher recruited the triple spy Pacifica Ocean and arranged a secret business proposition with Kazuhira Miller to help expand the Militaires Sans Frontières. However, Cipher's ultimate aim was to manipulate Big Boss into participating in the project without his knowledge.
Cipher ordered their agent to modify the MSF's Metal Gear ZEKE when the time came, and convince Big Boss to rejoin Cipher by threatening to frame MSF for launching a nuclear warhead at the United States if he refused. Ultimately, this plot failed when Big Boss damaged ZEKE and stopped the nuclear launch. Miller had also been unaware of Cipher's plot to discredit MSF. Meanwhile, Cipher planned to use the sons as insurance against Big Boss should the time arise.
In March 1975, Zero heard about the attack on MSF and that Big Boss survived the incident but had fallen into a coma. Having his suspicions on who was behind the attack, Zero contacted EVA to head the operation to move his comatose friend, Miller, and an unconscious medic from Colombia to a safe hospital in Cyprus. He then devised a plan whereby the medic would be transformed into Big Boss's "Phantom" (body double) through hypnotherapy and plastic surgery to make him believe he was the real Big Boss so that he could act as his public face until the time came for his resurgence. He requested Patriot operative Ocelot to look over Big Boss, and for Miller to await Big Boss's return to lead Diamond Dogs.
Ultimately, Zero learned the hard way that Skull Face had planned for years to attack him, as Skull Face wanted to free himself. As Zero spent his time in hiding and relayed orders via proxies since the cloning project, Skull Face never had an opportunity to track him down until Paz's survival was discovered. He then had her abducted, ostensibly due to her being a traitor to Cipher, to gain information on where Zero was located, as she was the only agent to have actually met Zero face-to-face. During this time, Zero had been undergoing treatment secretly at 10th Avenue of Hell's Kitchen in New York City.
Skull Face learned of Zero's hideout after successfully tricking Paz at Camp Omega. Not long after Skull Face attacked MSF, he sent Zero a pin, a very close copy of the Winged Dagger pin that was once owned by The Boss, which was laced with a strain of parasite that would eventually reduce Zero to a vegetative state, supposedly as he recovered from The Boss' body in Russia. During the "business call" supposed to confirm Zero received the package, Zero pricked himself while examining the pin, the wound became the vector for the parasite to enter his body; by the end of the phone call, the parasite began to take effect, leaving Zero in debilitating pain.
Although the best physicians attempted to delay the effects, Zero was resigned to his fate. He secretly arranged for the DARPA AI developer Strangelove, who had resigned from MSF over a week before the failed inspection initially not been aware of DARPA's connection to Cipher, to develop for him an AI network to take over the Patriots, having already lost faith in the new generation. However, she was eventually forced out after a "certain incident." He then left command over to Donald Anderson, more specifically the central AI that Anderson oversaw. He also gave the AI specific rules to follow in order to avoid a repeat of the Mammal Pod's hacking into NORAD during the Peace Walker Incident. However, Skull Face and the XOF took over Cipher's operations to more effectively carry out his plans of destroying the English language, forcing Zero to rely on his own resources to effectively hide from Skull Face.
By 1977, he also paid Big Boss a visit in Cyprus and intended to bid him farewell and presumably bury the hachet between them. In order to ensure his disappearance and destination was kept secret, he also orchestrated a blackout in New York City that same year that disrupted communications and transportation via two submarines, also giving a cover story. He also arranged for Ocelot to a body double to be created, a code word for indicating Venom had been awakened, and also notified Ocelot about this development and tried to assure Miller that he wasn't responsible for what happened to MSF. It is also implied that he may have told Miller about his debilitating condition.
By the time of Skull Face's death in 1984, Zero had fully entered his vegetative state and was relegated to life support. Years later, control of Cipher was given over to the Patriot AIs in accordance with his living will.
Unfortunately for Zero, what he had brought about had unforeseeable consequences: Namely, Big Boss ended up giving in to his darker nature and began fighting the Patriots and trying to bring about various wars, as well as conducting a coup d'état before being put down by one of the Les Enfants Terribles clones, Solid Snake, ultimately resulting in Big Boss being placed into a nanomachine-induced coma after Zanzibar Land. To make matters worse, thanks in large part to Anderson being forced to program them with the ability to learn for themselves after Strangelove was killed by Huey before she could implement traits such as compassion into the AIs, his AIs ended up completely abandoning his will and crafted their own, and even his closest allies Donald Anderson and Dr. Clark grew corrupt. The AI's deviation grew to a head the time of Solidus Snake's takeover of the Big Shell. By this time, the AIs fully crafted their own will: the S3 Plan and the war economy.
In 2014, Big Boss had awakened and then discovered Zero in a persistent vegetative state kept alive solely by life support equipment. After a computer worm destroyed the Patriots' AIs and Old Snake (Solid Snake) defeated Liquid Ocelot, Big Boss took Zero's wheelchair-bound shell to The Boss's grave in Arlington National Cemetery. Big Boss lamented that this man had nearly "brought the world to the brink of ruin" without even realizing it. Reflecting on their past experiences, Big Boss switched off Zero's life support equipment. As Zero was struggling to breathe, Big Boss pressed his hands over Zero's chest to stop him from moving as he died, ending the dictatorship he unwittingly created and putting his former friend to peace.
Personality and traits
Zero had a prominent scar over his left eye and also believed that he had once been abducted by aliens.
Due to his SAS training, he often looked down upon the American Armed Forces' methods of conducting operations, viewing them as sloppy, such as the fact that they relied too much on prepared equipment, such as a flashlight, or that they would leave their feces on the battlefield. The bomber jacket that Major Zero wore during the missions in 1964 resembled those worn by Allied pilots in World War II. It was also similar to the one worn by Steve McQueen in the 1963 film The Great Escape.
According to Zero's personal data as of 1964: his eyesight was 20/13; his blood type was "A"; he had previously been afflicted with gout; his hobbies included watching movies and hunting; his favorite food was Shepherd's Pie, while his least favorite food was hamburgers; he enjoyed spy and war movies; his favorite animal was the horse; his favorite type of liquor was whiskey; he enjoyed rugby; he liked Dimbula brand tea; and his favorite UMA was the Loch Ness Monster. Additionally, Zero disliked coffee and referred to it as "foul mud."
Zero was a huge fan of the James Bond films. Zero talked to Naked Snake about the intricacies and technological side of Bond's spy equipment and suggested that Snake be more like Bond, equipped with a "Snake shaped gun" and would get into an argument on the subject with Snake harboring a disinterest in the series and the spy genre in general. Zero also admitted that he personally didn't approve of how Bond interacted with female spies, after supposedly deducing one of the factors in Snake's dislike for the character. Sokolov said that Zero was a man of his word and a man of honor as he kept his promise to rescue him from the Soviet Union and apologized for being so late. In addition, Zero also was one who judged people on their merits rather than physical differences, as evidenced by his hiring Donald Anderson despite the former being banned from the workplace due to his ethnicity.
Zero had a keen eye for talent when recruiting operatives for missions, as he was responsible for recruiting several talented soldiers, mercenaries, spies and even assassins including Big Boss, Revolver Ocelot, Para-Medic, Sigint, Paz, Skull Face, and numerous others who would later become famous throughout the years. The Major had a particular interest in recruiting oddballs, people who displayed unique combat abilities, physical features, or even mannerisms that was often considered out of the ordinary in most people's eyes. One example of this would be Zero's recruitment of Skull Face, who had impressed the Major with his skills as an assassin and military tactician despite his horribly disfigured appearance. Another example would be Zero's recruitment of Paz, being impressed by her keen senses and ability to fool others using her youthful appearance, using her to infiltrate Big Boss's mercenary group MSF as way to keep tabs on him as well as to steal Metal Gear Zeke once it was completed, although she had ultimately failed her mission and was later captured by Skull Face, who used her to strike against the Major.
Of all his recruits, Zero's most complicated recruit was also his best recruit, Jack, the man who would become the legendary mercenary Big Boss. Upon meeting him, Zero knew he had chosen the right man for the Virtuous Mission, being impressed with the young man's military record as well as Jack's training underneath with his old ally, the Boss. While they had little in common, both were deeply motivated by the Boss's final words before dying, and chose to live the rest of their lives trying to rebuild the world the Boss always strived for. As time went on, Zero came to see Jack as the greatest soldier he ever had the pleasure of working with, surpassing even his mentor. while he had complete faith in Jack's abilities, Zero knew he wasn't invincible and would eventually die in the field or of old age, something that Zero saw as unacceptable. Knowing that Jack was sterile due to his exposure to radiation, Zero took it upon himself to carry on Big Boss's legacy and decided to clone him without his knowledge, knowing that he wouldn't approve. Big Boss was initially allied with Zero in joining the Patriots until he found out about the Les Enfants Terribles project, causing him to leave the Patriots, an act which Zero saw as unacceptable.
While their relationship remained strained for many years, Zero continued to look out for Big Boss even though the later wanted nothing to do with him. Zero even went out of his way to protect Big Boss after the attack on Mother Base, placing the comatose soldier in a British military hospital in Cyprus to protect him from Skull Face and XOF, who had gone rogue and poisoned Zero with a Parasite strain that would eventually leave him in a vegetative state. Knowing that XOF had taken over most of Cipher's assets and operations worldwide, Zero was left with limited resources and time before he would lose his mind, and used his remaining days making sure that Big Boss was well protected, going so far as to cooperate with Ocelot in creating a body double out of one of Big Boss's most trusted soldiers who was also in a coma, subjecting the man to extensive plastic surgery and hypnotherapy to transform him into Big Boss's Phantom. Before going back into hiding, Zero told a comatose Big Boss that the world will need him when he wakes up. One of Zero's final orders before disappearing was promoting Donald Anderson as the acting leader of what was left of Cipher, leaving him to develop the A.I. program that would eventually take leadership of the Patriots.
Zero didn't know much about technology and would use Sigint's notes when explaining what the anti-personnel sensor, motion detector, and active sonar were to Naked Snake. On a related note, he once bought a washing machine but didn't know how to use it.
After founding the Patriots to carry on The Boss's will, Zero over time became power hungry and a dictator by collecting more wealth and to gain more influence within the government. As a result, he also had no qualms for using Big Boss as an icon and to clone him without his knowledge. After Big Boss left the Patriots, Zero felt betrayed and lost his faith and belief in everything. By 1974, he also lost his ability to keep his promises and his code of honor by this point by his nearly having the Militaires Sans Frontières framed for a nuclear strike against America when Big Boss refused, despite this going against his promise to allow MSF to expand to Kazuhira Miller when getting him involved in the plot. In addition, after going into hiding as a result of Big Boss leaving the Patriots after he found out about the Les Enfants Terribles project, Zero did not directly give orders to his agents, instead supplying them to proxies and left his whereabouts unrevealed to all except for one agent, Pacifica Ocean, and even then, she implied at one point that she occassionaly got orders via proxy instead of from Zero directly, indicating that Zero had become paranoid. His paranoia was also shown in that he initially limited what would eventually become the Patriots' AIs and limited them to information sorting specifically to avoid recreating a similar near-disaster during the Peace Walker Incident in 1974, where The Boss AI proceeded to drown itself before it could start a nuclear war. Ironically, Skull Face's actions against Zero and later Strangelove's death at the hands of Huey ultimately resulted in the Patriots' AI network's ban on thinking for itself being removed (and thus, ultimately proving Zero's concerns about them possessing independent thought to be very sound in the future) due to Donald Anderson, being promoted to the de-facto leader of the Patriots in Zero's place, being forced to implement broad instructions and programming them to learn for themselves due to Strangelove dying before she could implement traits such as compassion into the Patriots AIs' network.
In 2014, regarding Zero's actions, Big Boss wondered if Zero hated or feared him. Although he never heard this as he was in a coma when Zero said this, Zero always considered Big Boss a good friend and had nothing to do with the decimation of MSF. He didn't care about Skull Face attacking him with vocal parasites, but never forgave him for putting Big Boss in a coma.
"Zero" is a British military radio term, often used as a callsign for a HQ. It also refers to a ghost, which Zero claimed was also fitting for a sneaking mission. Zero also referred to himself and the Patriots as "Cipher" which means "empty" and the number zero. This became fitting after Zero lost his beliefs and faith in everything when he became an empty shell of his former self.
Behind the scenes
Metal Gear Solid 3: Snake Eater
In the Japanese version of Metal Gear Solid 3: Snake Eater, Major Zero's (ゼロ) voice was provided by Banjō Ginga, who also voiced both Liquid Snake and Liquid Ocelot.
Zero's real name, David Oh, was first given in a voice casting sheet for Metal Gear Solid 3, which was leaked prior to E3 2004. It is mentioned in the Metal Gear Solid 4 Database and by Ocelot in an audiotape in The Phantom Pain.
It's possible that his character may have been at least partly inspired by Colonel David Stirling (otherwise known as Phantom Major), a real life British Army officer who acted as the founder of the Special Air Service (SAS). Aside from sharing a first name they also share a similar age, military background and philosophy regarding the effectiveness of small military special forces units.
The name Major Tom, while mentioned in-game to be a reference to The Great Escape, is also a character in the song "Space Oddity" by David Bowie. This could be a nod to the song, as it was originally selected as the ending theme for Metal Gear Solid 3 as it references space exploration. However, as the game ultimately departed from this theme, it was replaced by Starsailor's "Way to Fall."
In the Operation Snake Eater Briefing, Zero provides a Cuban cigar to Naked Snake, despite the fact that Cuban imports were illegal in the United States in 1964 and remained so until the ban was lifted by President Barack Obama in 2016.
Two radio conversations, relating to the Raikov Mask and the completed Raikov disguise, will have Major Zero commenting regarding the mask's "nostalgic" feeling that he "for some reason doesn't like it" and that Naked Snake's wearing of the Raikov disguise "is starting to irritate [Zero] already," referring to the negative fan controversy regarding the character Raiden from Metal Gear Solid 2: Sons of Liberty.
Metal Gear Solid: Portable Ops
Although Zero is imprisoned during the events of Metal Gear Solid: Portable Ops, he can still be recruited as a secret character. Simply complete the game with a Metal Gear Solid: Digital Graphic Novel save file on the PlayStation Portable's memory stick or use a code.
Zero's true involvement in the game is briefly hinted at during Gene's conversation with Ocelot in a cutscene, where he identifies Ocelot's co-conspirator as "the man with the same codename as 'Null.'" "Null" is the German word for "Zero."
- "Commander of Special Forces unit FOX, it was he who proposed the establishment of the unit to the CIA. Led Operation Snake Eater, providing support to Snake via radio. President of the unofficial UMA Finders Club at the CIA."
- ―Character description in Metal Gear Solid: Portable Ops Plus
Prior to the release of Metal Gear Solid 4: Guns of the Patriots, some fans had speculated that Zero was the "deviously cunning strategist" that Gene had mentioned in Portable Ops. Upon first viewing, the game's dialogue does not immediately make clear that this strategist and "the man with the same codename as Null" (Zero) are two distinct characters. However, later games reveal that Zero had continued to admire and idolize The Boss, causing opinion to shift towards Hot Coldman being the strategist, after he was revealed to be the planner of Operation Snake Eater in Metal Gear Solid: Peace Walker.
Metal Gear Solid: Peace Walker
While Zero does not make a physical appearance in Peace Walker, barring his secret phone call with Miller and Paz's flashback, he is referenced multiple times. In one of the briefing files, Big Boss reminisces about Zero hating coffee in a conversation with Paz. In another briefing file, it's implied that Big Boss is thinking about Zero when Paz mentions that she does not understand why "friend turned against friend" while describing Costa Rica's civil war. In addition, during the attempted destruction of the Mammal Pod in Chapter 4, one of the glitched statements by the Mammal Pod was "The Lonely Fox Chases The One Eyed Hound", hinting at Big Boss and Zero's feud. In the Date Paz mission, Paz when she's sleep talking will sometimes say "Yes sir... I understand" in a different tone of voice, with it being implied that she was flashing back to a conversation with Zero.
"David Oh" is a dog tag that can be collected in Metal Gear Solid 2: HD Edition. It is ID 026 and can be found during the Tanker Chapter on the Extreme difficulty setting. However, the David Oh the dog tag belongs to was born on July 14. Zero was born on August 12.
Major Zero appears in Versus Battle.
Master Manipulator of the Oval Office
Big Boss, Slowly Consumed by Power
SAS-trained, Zero formed the CIA’s special forces FOX unit with the Boss, and then the Patriots with the Big Boss, and lost himself to power in the process
METAL GEAR SOLID: THE LEGACY COLLECTION"
- ―Major Zero's bio on Versus Battle
Zero is heavily alluded to in Metal Gear Solid V: Ground Zeroes. He is also an unlockable character in the Ground Zeroes app, acting as an officer character in the Mother Base Developer. To unlock him, the player must obtain 50k+ points on Hard Mode of Destroy the Anti-Air Emplacements while connected to the app.
Hideo Kojima revealed on Twitter that Banjō Ginga, Zero's Japanese voice actor, would play a role in The Phantom Pain, although it was unconfirmed at the time whether Zero himself would actually appear in the game. Zero's English voice actor, Jim Piddock, stated on Twitter that he elected not to reprise his role as Zero, and implied it was due to a payment dispute with Konami. Piddock later elaborated on the reason for the refusal in an episode of The Codec, explaining that, because Zero had a limited physical presence in the game, Konami felt justified in giving him what he believed was too small of a payment for his voice work for the character. He also implied that Zero would be mostly heard instead of seen. In addition, Zero is heard talking about The Boss in the E3 2015 trailer of The Phantom Pain.
- Metal Gear Solid 3: Snake Eater
- Metal Gear Solid 3: Subsistence (Secret Theater; non-canon)
- Metal Gear Solid: Portable Ops
- Metal Gear Solid: Portable Ops Plus (non-canon)
- Metal Gear Solid 4: Guns of the Patriots
- Metal Gear Solid: Peace Walker (off-screen, mentioned and flashbacks)
- Metal Gear Solid: Social Ops (trading card)
- Metal Gear Solid V: Ground Zeroes (off-screen, unintelligible voice and mentioned)
- Metal Gear Solid V: The Phantom Pain (mentioned and voice)
- ^ Metal Gear Solid V: The Phantom Pain, Kojima Productions (2015).
- ^ a b c d e f g Metal Gear Solid 3: Snake Eater, Konami Computer Entertainment Japan (2004).
Radio Mode, Personal Data. 
- ^ a b http://www.tentenpro.com/muni_shinobu/mgs3/leak.html
- ^ Metal Gear Solid 3: Snake Eater, Konami Computer Entertainment Japan (2004).
This is implied in a radio conversation between Zero and Naked Snake during the Virtuous Mission.
- ^ Metal Gear Solid: Portable Ops, Kojima Productions (2006).
Naked Snake: Does anybody read me? This is Snake. If anybody can hear this, please respond. // Para-Medic: Snake! Is it you? Is this the real Naked Snake? // Snake: That voice... Para-Medic? // Para-Medic: It's me! It's been a while, huh, Snake? It's good to hear your voice again. // Snake: Same here. It'd be even better if I weren't in this god-forsaken place. So, you're still using this circuit? // Para-Medic: Major Zero kept it just in case. He said if you were safe, you might try to use it to contact us. To be honest, I never really expected you to call. But I'm glad you did.
- ^ Metal Gear Solid V: The Phantom Pain, Kojima Productions (2015)
Benedict "Kazuhira" Miller: [...]According to the man you extracted, their orders came through the same channel as always But is Zero really able to give orders in his current state? Or is somebody else calling the shots for XOF? For Cipher? What the hell...
- ^ The latter is mentioned by Sigint in a radio conversation, should the player manage to procure the Spirit camo.
- ^ Metal Gear Solid V: Ground Zeroes, Kojima Productions (2014).
Info > Paz's spy log: Big Boss & Mother Base > Communications Record 2 (Correspondent Unknown)
Paz Ortega Andrade: Yes, things are...proceeding. But modifying ZEKE has not proven easy. I'm using Zadornov to buy some time. [...] No, I have not forgotten what you said. However... Well, forgive me for asking, but... this is you I'm speaking to, isn't it... Cipher [Zero]? communication ends I must... I will fight Big Boss. The world must be ruled by a single will... To defy Cipher is a fate worse than death.
- ^ http://www.usatoday.com/story/news/world/2016/10/14/obama-cuba-regulations-expands-trade-travel-rum-cigars/92042662/
- ^ Metal Gear Solid: Peace Walker, Kojima Productions (2010).
Briefing File > Paz > Costa Rica > The Civil War
Paz Ortega Andrade: What I don't understand is why friend turned against friend when they could have talked it out instead. // Naked Snake (Big Boss): Yeah, that... would have been nice.
- ^ http://www.metalgearinformer.com/?p=16766
- ^ http://www.metalgearinformer.com/?p=16795
- ^ http://www.metalgearinformer.com/?p=20712
|Metal Gear Solid 3: Snake Eater characters|
| Naked Snake — Major Zero — Para-Medic — Sigint|
The Boss — Colonel Volgin — Ocelot — EVA
The Pain — The Fear — The Fury — The End — The Sorrow
Sokolov — Granin — Raikov — Johnny — DCI
Nikita Khrushchev — Lyndon B. Johnson — DOD Official — KGB Chief Director
|Metal Gear Solid: Portable Ops characters|
| Naked Snake — Roy Campbell — Jonathan — Para-Medic — Sigint|
Null — Gene — Python — Cunningham — Elisa and Ursula
Colonel Skowronski — Sokolov — Ocelot — EVA — Major Zero — Raikov — DCI — CIA strategist — DOD Official
Teliko — Venus
|Metal Gear Solid 4: Guns of the Patriots characters|
| Old Snake — Otacon — Raiden — Naomi Hunter — Big Mama|
Liquid Ocelot — Vamp — Drebin — Little Gray — Solidus Snake
Roy Campbell — Sunny — Rosemary — Mei Ling — Little John
Meryl Silverburgh — Ed — Jonathan — Johnny
Laughing Octopus — Raging Raven — Crying Wolf — Screaming Mantis
Psycho Mantis — Zero — Big Boss