Doctor Eggman

Dr. Ivo Robotnik (ドクター・ロボトニック), better known by the alias Dr. Eggman (ドクター・エッグマン), is the main antagonist of the Sonic the Hedgehog series. He is a human and the arch-nemesis of Sonic the Hedgehog. This large scientist with an IQ of 300 dreams of dominating the world, but his constant plots to create his Eggman Empire are always thwarted by Sonic and his friends.

While the doctor's plans initially consisted of building incredible armies by turning animals into robots and using them to dominate the land, Dr. Eggman's schemes have since branched into much more global threats as he built war machines, used nuclear devices to threaten entire nations, and even relied on mythological and ancient deities bent on destruction to achieve his goals. Eventually, the mad scientist has gone as far as to target the entire universe and cooked up schemes to control time and space itself.

While all these plans end in failure thanks to the continued efforts of Sonic and his friends, the mad doctor is somehow always able to slip away from certain death or imprisonment and escape at the last moment, making him a constant threat to the universe and a thorn in Sonic's side.

Concept and creation
In April 1990, Sega petitioned its research and development department, AM8 (later became Sonic Team), to create a character who would replace Alex Kidd as the company's mascot, as well as compete against Nintendo's flagship character, Mario. A caricature of Theodore Roosevelt in pajamas was among the proposed designs. Combined with the idea of an egg-shaped character, it eventually became the basis of the visual design for Dr. Eggman. In creating the "bad guy" for the Sonic series, the development team wanted a character who was "the opposite of Sonic"; a character who represented "machinery" and "development" to play on the then-growing debate between developers and environmentalists. The character was also designed to be easy for children to draw.

Although Eggman was always depicted as having pince-nez glasses in Japanese media, initial American localized material, including the covers for Sonic the Hedgehog 2 and Sonic the Hedgehog 3, frequently depicted Robotnik as having no eyes in his eye sockets (or, in the case of various cartoon adaptations, having black sclera and red pupils), and was not depicted with eyewear in localized materials until Sonic Adventure. The original English instruction manual for his 1991 debut game Sonic the Hedgehog described the character's full name as "Doctor Ivo Robotnik" while the Japanese version's instruction manual for the same game called him "Doctor Eggman"; "Robotnik" was initially conceived as the western name for the character. In 1998's Sonic Adventure, he was referred to with both names, the doctor calling himself "Robotnik" and the rest of the characters naming him "Eggman", with all following English releases to date referring to him as the latter.

Yuji Naka has explained that Robotnik is the character's true last name while Eggman is a "common name taken after his shape."

While "Robotnik" is still occasionally recognized in more recent titles (such as in Sonic Generations), Eggman's profiles such as the one on the Japanese Sonic Channel and Sonic the Hedgehog 4: Episode II list his full birth name as unknown.

Appearance
In general, Eggman is depicted as being rotund in appearance. He possesses a dome-shaped head and no visible neck, a bald head, a bright red nose, and a very bushy mahogany moustache. During his early years, Eggman had a completely round torso with normal-looking arms and legs. Back then, he also wore a red shirt/jacket with yellow triangles (which can be described as either a collar or part of a cape, which can be seen on his back), with black pants with connected boots and silver-colored round buckles, white gloves, and mirrored pince-nez glasses.

In the present day, Eggman remains obese, but has become somewhat burlier, taller and less flabby with long, almost disproportionately thin arms and legs. He now wears both his tinted glasses and green-lensed goggles as headwear, though his mustache retains its length, density and mass. Gone are the cape and his suit-like clothes, in their place an elegant, red coat sporting two square metal buttons on both sides of the chest in gold. These buttons have white straps that run across the coat's sides to identical buttons on the back. The coat also has silver, zipper-like linings down the back, arms and front, yellow cuffs, and two extensions on the front that have large silver buttons. In addition, Eggman also wears white, cuff-less gloves on his hands and a pair of black pants with matching boots seemingly attached to them bearing circular plates on the both sides of the ankles and three square ones riding up the shin.

In Sonic the Hedgehog (2006), he was given a radically different appearance owing to the more realistic designs of the game. In particular, he has yellow bolt-like buttons on his red coat where the buckles were originally, as well as a slightly raised collar obscuring his chin. His moustache, while still bushy, also looks more groomed, and he also, while still overweight, looks very lean by comparison to his usual designs. His nose is also colored the same as the rest of his skin.

Personality
Eggman is a short-tempered, raucous, pompous, and cruel evil genius who is constantly planning to take over the world. His primary motivation throughout most games is his psychotic belief of self-entitlement. Arrogant and narcissistic, he constructs countless technological wonders in his own image to fuel his massive ego, usually reinforced by his goal of finally constructing the Eggman Empire, and doesn't care where it starts. His narcissism is such that when he first discovered the Phantom Ruby, what it showed as his deepest desire was Eggmanland complete with various labels of his names and statues to himself, and was saddened when the illusion ended.

Although Eggman is a villain, he helps Sonic when the world is at stake; though the reason is always because he knows there would be nothing left for him to conquer if the planet was destroyed. In some of his incarnations, he actually displays a begrudging respect of his arch-enemy, Sonic.

Despite his intelligence, Eggman can be very immature, throwing temper tantrums when Sonic manages to wreck into his plans. An example of his immaturity is in the ending of Sonic Unleashed, when Orbot begins to insult him over his constant failures and calls him a loser; Eggman screams "Oh, shut up!!", attempts to kick him only to comically fail, and then chases him through the desert while making agitated noises and violently flailing his arms in an attempt to grab him.

Although Eggman is known for childish outbursts when angry, there are a few rare instances where he comes across as stoic and even-toned when extremely aggravated or during very serious situations. Notable instances of this include the Station Square incident, after Tails not only beat him to his crashed missile but also disarmed it, leaving any chance at him destroying Station Square to be impossible, he proceeded to threaten the young fox while barely even raising his voice; and the Deadly Six incident, where he, after being taunted by the then-renegade Zeti about their impending destruction of the world via their stolen Extractor, threatened them in an even-handed manner to destroy everything they desired before smashing the ice-block communication set they were using and retaining this tone when telling Orbot his hands are okay from smashing the ice blocks so long as he can strangle a Zeti with his bare hands.

Eggman seems to overlook crucial details in his plans, such when he orders his robots to fire at Sonic while he is escaping with Princess Elise, failing to realize that they could possibly injure or kill Elise if they land a direct hit on Sonic and overlooking Dark Gaia's immature release. He also was shown in Sonic Colors to be somewhat sarcastic, as evidenced when questioned by Orbot and Cubot as to whether he wanted the remaining aliens, to which he told them in a flippant manner that he actually wanted a cheeseburger and a shake. Similarly, he has occasionally utilized a rather bleak sense of humor, such as in Sonic Colors with his PA announcements at Starlight Carnival, where he says in one of them "We seem to be losing pressure on level seventeen. Please hold your breath against the harsh vacuum of space until you pass out from oxygen starvation. After that, you won't care. Enjoy the ride!", as well as in his propaganda video "Come Join the Eggman Empire", where he jovially narrates that being in an area filled with pollution is a lot better than with clean air especially after a robotomy treatment that saps its citizens of their ability to eat, sleep, and think ever again that he claimed was the "good life."

While Eggman's motives for conquering the planet and attempting to wipe out entire populaces are never made clear, what is clear that Eggman is primarily concerned about obtaining power and dominance for himself, with his violent tendencies and insanity mounting as the series continues.

To this end, Eggman has never shown a willingness to do good or help others without it serving his own ends in some shape or form. While displaying a comical disposition later on in the series, he is quite clearly a cruel minded and brutal man who will use any opportunity presented to him to fuel his self-serving desires, even if that means exploiting worldwide catastrophes to obtain power and dominance. From abducting and transforming animals into robot armies, to leading large scale attacks on a terrorist level, Eggman's numerous crimes and exploits continuously transition into more destructive ramifications. He never acknowledges the results of his actions such as the pollution from his fortresses and strongholds that poison the surrounding environments or the ruins that are left from his own attacks on various cities and lands. His exploits have led to numerous tragic events, such as Chaos flooding and utterly destroying all of Station Square and Dark Gaia nearly consuming the whole planet, as well as threatened the welfare of time, space, and the universe itself.

However, despite his desire for world domination, Eggman does have a human side, and does not appreciate senseless destruction, tormenting and killing from other individuals and forces who are beyond his control. In Shadow the Hedgehog, he is shown to be disgusted and shocked at the thought that his own grandfather would sacrifice his own people for the sake of research and aid the Black Arms. This demonstrates that even if Eggman does not mind causing chaos and destruction, he ultimately knows that there is a line that others should not cross and was afraid his grandfather did so through betraying humanity and aiding a species that wanted to eliminate the human race. This shows that the doctor has some form of loyalty to the human race and could not fathom the idea of betraying his own species to that of a vicious and demonic alien empire, despite some of their actions mirroring his own in terms of the scope of their plans and the destructive ramifications of their actions.

While this seems contradictory towards Eggman's previous exploits of joining forces with other creatures bent on destruction, it seems that he still wishes to paint his grandfather in a positive light as he was his hero in his childhood. This more humane side to the doctor is shown in full force at the end of Sonic Adventure 2, where he has an honest and genuine conversation with Tails about how much he adored his grandfather, questioning the actions of his fallen idol and wondering if he intended to destroy him as well. Additionally, in Sonic Lost World, he unhesitatingly jumped in to save Tails from being attacked by a Crabmeat-controlled Cubot, and when questioned by Sonic over having rescued one of his worst enemies, Eggman admits that he's "a complicated guy."

Despite this, Eggman seems to have no problem in committing senseless killing and destruction as long as he is the one in control of the forces doing so. It would seem that the doctor is so bent on authority, that he refuses to let other forces destroy his planet unless they are under his complete control. This is shown when Chaos betrays Eggman and floods all of Station Square, an action that Eggman had planned Chaos to do from the very beginning regardless of the beast's betrayal against him, but refused to allow his rampage to continue as Chaos was no longer under his control. Additionally, in Sonic Adventure, he launched a missile deep into the heart of a heavily populated Station Square to utterly destroy it, even if that meant killing himself (even going as far as to state 'I'll take the whole city with me'), as a twisted form of revenge and victory over Sonic after his plans to use Chaos to dominate the planet failed. In Sonic Adventure 2, his desire for destruction appears at its height as he laughs insanely at the Eclipse Cannon's impending firing at the planet, which would have had devastating effects to billions of lives, until his grandfather's true operations were activated. He also admits that had he had the chance to use the space colony ARK to collide with earth, he would've done so a long time ago, showing admiration towards his grandfather's mad projects, and only decides to prevent them from coming to fruition in order to save his own life as escape was impossible with the colony on its collision course.

In Sonic Unleashed, there is a possibility, realistically speaking, that he murdered millions when reawakening Dark Gaia by splitting the planet itself apart, though the effects of the quake in relation to the earth's populace is never touched upon. In Sonic Lost World, Eggman contemplates destroying one of his own doomsday machines to ultimately destroy the Deadly Six, even if it means taking many innocent lives with them, much to Sonic's disgust. According to his PA announcement in Sonic Colors, his park can be considered a lethal weapon in itself as most of the rides lead to horrifying and agonizing deaths and circumstances should anyone ride them. Lastly, in the beginning of Sonic the Hedgehog (2006), he orders his robots to launch numerous missiles at Sonic with no regard for any that may be caught in the crossfire.

Regardless of how many lives may or may not have been lost to Eggman's various schemes, the evil scientist clearly demonstrates a complete disregard for all life, even his own on occasions, as well his own creations, and will go to any means necessary as long as his goals of destroying Sonic and his friends, conquering the planet, and establishing his empire are met with full success. With the means for Eggman's plans to succeed often resulting in massive amounts of chaos and destruction, the success of his schemes would also result in a world slowly dying away from Eggman's ruthless and tyrannical rule.

Sonic Forces showcases a world nearly conquered by Eggman and his forces, with the villain going as far as to attack and utterly destroy entire cities in order to drive out and eliminate the last pockets of resistance against his rule, and has even gone as far as to plan to conjure a second sun to crash down on the earth to wipe out any remaining pockets of resistance, making clear that he intends to recreate the earth to be his Empire from its ashes as a result. While urban areas are utterly devastated, the areas previously overflowing with nature are now slowly dying, as Eggman's forces begin constructing fortresses and factories throughout, depleting the area's resources and causing massive amounts of pollution, which eat away at the surrounding environments. In addition, in his capitulation message requesting for the resistance to surrender and trying to negotiate the terms of surrender, he lets slip that he intends to lock them away in an underground prison before stopping himself.

The various, dark futures within Sonic CD also provide a glimpse of the horror that would be a world under Eggman's control; twisted steel, pollution, and ruin, to the point that even Eggman's own creations are in pitiable states, illustrating that once Eggman has seized control of the world, he will become a ruthless tyrant who will exploit all of the planet's resources to the point that they are polluted or depleted as even his own creations suffer. This could imply that once Eggman has conquered the world, there will be little need of his robotic army as he primarily uses them to conquer territory and will be seen as expendable to him and left to rot. This would further be indicative towards how Eggman has previously treated his robots if they failed him, ordering torturous redesigns on his various E-Series robots if they did not complete their missions and even abandoned Orbot and Cubot in the vastness of space without a second's hesitation, though they would later rejoin the doctor sometime later despite this. Also, in Sonic Lost World, Eggman is content with conquering what is left of the world after the Deadly Six's actions, supporting that Eggman does not care what condition the world is in as long as he is the one ruling it.

Perhaps the most frustrating and deadly aspect about Eggman is his tendency to always escape at the last minute, even as all his creations and machines crumble and blow up around him, ensuring that he will always be back again with another scheme to endanger the planet and beyond. No matter how close Sonic appears to be finally catching the villain and putting him out of commission, the doctor always has an escape plan, which ironically enough, are the only plans he can formulate that Sonic has been known to fail in foiling, making it nearly impossible for both individuals to defeat the other for good, making their battle a never ending one.

One of Eggman's more admirable, if not dangerous, traits is his courage throughout life threatening situations. Despite Eggman's continuous use of machinery to both protect himself and fight his opponents, Eggman shows considerable bravery and very rarely shows fear, regardless of who or what he is facing. Even in the wake of the Black Arms invasion, Eggman remains very composed and even enters their base of operations without showing any fear. His persistence to control other creatures bent on mass destruction and approach them to ultimately tame them, including Chaos and Dark Gaia, also illustrate his apparent lack of fear. However, if he's caught without any backup plan to fall on, he isn't above fleeing, such as when the Deadly Six took over his army after Sonic kicked away his Cacophonic Conch.

Eggman, while sending out his army to do most of his dirty work, has also been known to lead missions personally with himself in the field for both amoral and noble deeds, though with self serving interests always at the forefront of his mind. His apparent lack of fear during these missions can be owed partially to the fact that Eggman has previously shown a disregard for even his own life on several occasions (as in the case of his attempted suicide bombing of Station Square with a missile), as long as his plans come to full fruition. In Sonic Adventure 2, Eggman tells Shadow that he might not survive his battle with Sonic in the space colony ARK and instructs him to finish their plans to use the Eclipse Cannon to dominate the planet and possibly even use the weapon to destroy large portions of it. While the villain has been known to panic when his plans spiral out of control, especially when victory previously seemed assured, he is always able to compose himself long enough to either finish the mission at hand or escape at the last minute.

Ultimately, while not openly violent and ruthless, Eggman is still a highly brutal and amoral villain with an insatiable lust for power, dominance, and, since meeting Sonic, revenge. While still harboring a more humane side and displaying comical undertones, Eggman's ruthless and violent nature can still be seen throughout the series. His uncompromising persistence shared with his appetite for authority and control fuel the conflicts throughout the entire series and guarantee that Sonic will always be needed to stop him.

Powers and abilities
Eggman's most well known ability is his masterminded plots and schemes which only fail due to Sonic and his friends. He is a remarkable scientist and engineer, as evidenced by the numerous armies of robots, warships, and other mechanical inventions he has created. Eggman also has incredible skill in operating various vehicles, from his own Egg Mobile, to his various mechs, to racecars like the Egg Booster. In fact, his rivals as a machine pilot is rivaled only by Eggman Nega and Tails.

Owing to his masterminding plots and schemes, he was also shown to be a genius in strategy and tactics, which was best demonstrated twice: The first time was in Sonic Adventure 2, where Eggman not only came up with the plan to neutralize the Chaos Emeralds, but also guided Tails, Rouge, Knuckles, and Sonic through the path to the Cannon's Core and advised them on how to bypass the various security measures, and even gave some tips on how to defeat the Finalhazard, and even earlier managed to deduce that Sonic and his friends were planning to use a Fake Emerald to undo his plan and proceeded to outsmart them by trapping Sonic, anticipating that he had the fake emerald (and tricking Tails into confirming it). The second time was in Sonic Forces, where he not only made sure to build a backup generator for the Phantom Ruby due to anticipating the possibility that the Resistance would destroy the primary one, but also left disinformation about how the Phantom Ruby was actually generating power and leaving the "generator" as a decoy.

Eggman has considerable physical strength as seen in Sonic Lost World where he was able to shatter a large wall of ice with his bare hands, and in Sonic Riders, Eggman is classified as a Power Type, further implying a high level of strength. As seen in some games' endings he is also quite resistant to damage, being catapulted or falling vast distances only to come out scratched up but mostly unharmed.

Despite his physical structure, Eggman is also very athletic; during their early battles, there is almost always a point where Sonic chases Eggman and despite of his weight and Sonic's speed, he always manages to outrun his nemesis long enough to reach his next escape vehicle or weapon. In one cutscene of Sonic Lost World, Eggman flees from the Deadly Six around the same pace as Sonic.

Equipment
Eggman's glasses are shown to be a highly advanced technological eyewear. With it, he could locate the Chaos Emeralds' locations in the corners of the distorted world after they were flung there by Solaris.

Sonic the Hedgehog
Eggman has many enemies throughout the series, but his arch-nemesis is none other than Sonic the Hedgehog. Sonic always thwarts the doctor's evil plans for world domination. Despite this, Dr. Eggman has teamed up with Sonic at times mostly whenever the planet is in danger by a greater force, showing that they can somehow go beyond their hatred and get along if the situation calls for it. Two examples being in Sonic Adventure 2 when he helps to stop the ARK from crashing into earth, and Sonic the Hedgehog (2006) where he aided the heroes in locating the Chaos Emeralds. In addition, in Last Story of Shadow the Hedgehog, shortly after Sonic tells Shadow to give him the Chaos Emeralds instead, Eggman says "Don't give them to Black Doom!", implying that he at that moment was even willing to let Shadow potentially supply the Emeralds to Sonic if it ensured that they didn't go to Black Doom instead. They also form temporary alliances in Sonic Chronicles: The Dark Brotherhood and Sonic Lost World. This could be because somehow, deep in his heart, he may have a certain fondness for the hedgehog's determination that was as fierce as his own over the years, and gained a certain respect for his constant adversary.

Sonic seems to tease Eggman a lot. It is thought that Sonic might have given him the nickname "Eggman," due to his body shape being an obvious target for criticism. While Sonic usually treats Eggman with playful disregard, Eggman generally views his enemy as either an annoyance or a threat. It is rare that he will ever taunt Sonic back, unless he holds the proverbial cards. It is an obvious fact that Eggman holds a grudge on Sonic most of the time, but in the Sonic Simulator Missions of Sonic Riders: Zero Gravity, Eggman says, "Now that's the Sonic I know! They don't call you the fastest in the land for nothing." Akin to this, Sonic can, at times, show that while he does not like Eggman, He does not desire for him to be seriously hurt or killed. An example of this can be taken towards the end of “Sonic Lost World”, where, upon Eggman’s apparent sacrifice of his own life to save Sonic from a deadly fall into lava, Sonic seemed to be both shocked and even somewhat disheartened by Eggman’s apparent death. However, when the Doctor made his return and claimed he planned on conquering the world as he had always planned, Sonic immediately taunted him and attacked him.

Eggman, ever prideful, maintains a facade that his concern is only for world domination and not Sonic's death, although there are times when he will directly challenge him. As players approach the end of the games, Eggman refers to Sonic in increasingly threatening ways and places greater priority on stopping him. Eggman has made eliminating Sonic his second goal under world domination. It is also implied that his attempts and failures to defeat Sonic may have driven him somewhat insane, as after revealing his plan to use the Time Eater to rewrite history to ensure he came out on top, the Present Eggman proceeded to laugh maniacally and excessively, causing his past counterpart to become disturbed that he may eventually become as crazy as his present self. However, when trapped in the void after both Super Sonics defeated them and the Time Eater, they ultimately admitted they will never be able to defeat Sonic. By the time of Sonic Forces, however, his hatred of Sonic grew to the extent that he created an invincible weapon of destruction to deal back all the defeats Sonic inflicted on him. Nonetheless, he did retain at least some grudging respect for his adversary, as shortly after Infinite's defeat, he admitted his surprise and impressment that Sonic was able to defeat his creation, although he nonetheless makes it very clear that he's impressed solely in the sense that it would make his defeating Sonic more satisfying.

Although part of a different continuity, the early Sonic canon shows Sonic and Robotnik as once being good friends, a side of them that's never seen in the games.

Classic Sonic
Dr. Eggman first fought against Classic Sonic during the Time Eater incident in an effort to erase him. He later re-encountered Classic Sonic during the War to Take Back the Planet. However, during that time, it was heavily implied that he considered Classic Sonic to be more of a nuisance than a true threat to him, especially compared to his Modern counterpart; when encountering him, he dismissed him as not being worth his time and tried to disengage him before ultimately fighting him, while by contrast he scolded Infinite for letting Modern Sonic live during their encounter at Mystic Jungle. He does, however, acknowledge that Classic Sonic has "a lot of nerve".

Miles "Tails" Prower
Tails is the only person to have ever been able to match Eggman in wits because they are both mechanical geniuses, which was the source of their rivalry over the course of Sonic Adventure 2. After that it seemed as if their rivalry had watered down, possibly because they had to work together. Once again, in Sonic Chronicles: The Dark Brotherhood, they had to work as allies, but this time they shared a mutual respect for each other, because they were both respected geniuses. In Sonic Lost World, Tails is very bitter towards Eggman and often insults him and acts sarcastically, in one cutscene it looks like they almost come to blows, however Sonic steps in. In that same scene, Tails seems upset and even angry because he believes Sonic trusts Eggman to stop the Extractor more than him. Despite this, Eggman saves Tails from Cubot when he attacks Tails because Tails had attached Cubot onto a broken Crabmeat, making him "very mean", as Cubot put it. Later when Tails is captured, Eggman says that they need to make sure that "his sacrifice wasn't for nothing" in a low somber voice, meaning that even though Tails doesn't trust him, Eggman may at least have some kind of respect or even care for Tails.

In Sonic Forces, they also engaged in a rivalry regarding their fields in a similar manner to Sonic Adventure 2, which was best demonstrated during Eggman's boss fight, where Tails, in response to Eggman's gloating about the power he had acquired surpassed even his expectations and that his own genius scared even him at times, cited that counted as a failure due to Eggman miscalculating, before Eggman pointed out that the ultimate of genius required surpassing expectations before stating Tails wouldn't understand. Another example of this was when Eggman's artificial sun plan failed: when Eggman expressed shock and anger at the presence of another Phantom Ruby prototype due to having attempted to make sure they were all destroyed beforehand, Tails rubbed in on the failure by reminding him that a "good scientist" always checks and doublechecks his theories.

Metal Sonic
Metal Sonic is one of Eggman's greatest creations, and his only robot that has come the closest to defeating Sonic. Despite Metal Sonic's loss to Sonic in Sonic the Hedgehog CD, Eggman did not lose hope in Metal Sonic, and has since rebuilt him several times to accomplish his various agendas, even to the point of summoning the original back from Little Planet.

In time, Eggman got betrayed by Metal Sonic in Sonic Heroes, where the robot seized the Eggman Empire for himself to rule the world and destroy Sonic himself. It is heavily implied that Eggman regretted this outcome, as he proceeded to answer Team Chaotix's interrogation of who locked him up with a saddened tone. However, Eggman did not give up on Metal Sonic even after that, and so reprogrammed Metal Sonic into his obedient servant again when regaining possession of him. Although Metal Sonic still displays rebellious tendencies, it has not stopped Eggman from using him for different missions. In Mario & Sonic at the Rio 2016 Olympic Games, Eggman and Metal Sonic share a special victory animation, where Eggman expresses his pride in Metal Sonic by patting him on the back, annoying the robot.

Knuckles the Echidna
The two were once partners, meeting each other for the first time in Sonic the Hedgehog 3 & Knuckles, where the doctor, having managed to land his Death Egg in Angel Island, would trick the echidna into believing Sonic and Tails were after the Chaos Emeralds for evil purposes, but later Eggman would reveal his true intentions to Knuckles by snatching the Master Emerald with his Eggmobile and electrocuting its guardian as he tried to protect the massive gem. As Knuckles noticed he had been deceived, he befriended Sonic and Tails and helped them defeat the evil scientist. Despite this, Eggman still did not give up after his defeat to the heroes, sending an Eggrobo and Mecha Sonic to eliminate Knuckles, but failed.

Ever since, Eggman has become the one person that Knuckles can't trust at all and one of his greatest enemies yet, but, due to Knuckles' guillible nature, he still seems to fall for his lies (especially in the earlier games). However, Knuckles has gotten better with this over the years and is more aware of Eggman's plans, even showing a rough attitude towards the doctor in later titles.

Doctor Eggman Nega
In the Sonic Rush series, the counterparts become partners to create their own Eggmanland, Sonic has even mistaken Eggman Nega for Dr. Eggman and thought that it was just a silly new disguise. However, in the Sonic Rivals series, Eggman Nega turned Eggman into a card, sparking some animosity.

It is likely that their alliance fell apart at the end of Sonic Rush Adventure when Eggman Nega nearly blew up the earth against Eggman's wishes. It is also revealed in Sonic Rivals that Eggman Nega is not Eggman's dimensional doppelgänger, but his descendant from at least 200 years in the future, though it's never made clear if Eggman himself knows about this fact.

Shadow the Hedgehog
Since Shadow was created by Eggman's grandfather, Eggman was after Shadow because he was stated as the "Ultimate Lifeform" which could help him conquer the world. When he released Shadow from his capsule, he thought that Shadow was Sonic, but then he realized that the hedgehog merely looked like his rival. He also ordered Shadow to work for him, steal all seven Chaos Emeralds, and to keep Sonic out of the way so that he wouldn't foil his plans. Everyone was shocked when they realized that Shadow was created to kill everyone on earth, even Eggman himself.

But after Sonic Adventure 2, Eggman seems to have a dislike for Shadow and told Shadow not to disturb him in Sonic the Hedgehog (2006). However, he depended on Shadow to eliminate the Black Arms in Shadow the Hedgehog, which nonetheless is the only game in which Shadow actually fights Eggman (as in Sonic Heroes and Sonic Rivals it was Metal Sonic and Eggman Nega in disguise though he does race him in Sonic Free Riders). Eggman in Shadow the Hedgehog was revealed to be the reason why Shadow was still alive, as he sent one of his robots to save him when he seemed to have perished during the ARK incident, although he nonetheless tried to trick Shadow into believing he was one of his robotic doppelgangers. In the Sonic Rivals series, Eggman turns to Shadow for help in defeating Eggman Nega. Though they still appear to be enemies whenever Eggman is the villain, Eggman does have great faith on Shadow's capabilities whenever they encounter a more dangerous evil.

In Sonic Forces, it seems that Shadow and Eggman are completely enemies. Eggman in particular seems scorned by Shadow, just like Sonic, and calls him a blasted Hedgehog. Despite this, however, he had no qualms with creating Replicas of Shadow for his Eggman Empire.

Orbot and Cubot
Eggman created Orbot to wait on him hand and foot in Sonic Unleashed, but Orbot has since gained a personality of his own, much to Eggman's annoyance. The two tend to argue with Orbot winning, Eggman retaliating by trying to hit him. At the end of Unleashed, Orbot continued to insult Eggman and his blunders, until Eggman finally snapped and chased Orbot off into the sunrise.

In Sonic Colors, Eggman is slightly more annoyed with Orbot and gives him more work to do. Orbot gained a more sarcastic tone and continued to seize any chance to insult Eggman. Orbot's counterpart Cubot's voice chip had malfunctioned and adapted to cowboy and pirate accents throughout the story, also much to Eggman's annoyance. At the end of Colors, Eggman is seen ordering Orbot and Cubot to push his Egg Mobile after it had lost power. Cubot was excited to have his regular voice back and began talking non-stop, which left Eggman exasperated. The official Sonic Colors website and manual also states that while Orbot obeys Eggman faithfully, he does not like him very much while Cubot, on the other hand, likes Eggman but tries to get out of doing any work.

Although Orbot generally does not give Eggman many compliments, there have been a few instances where he was capable of acknowledging Eggman, as evident in Sonic Forces where, while Eggman was gloating about how with his new weapon, he would defeat Sonic and succeed in conquering the world, Orbot admits that that time, Eggman "[meant] business".

Classic Eggman
Classic Eggman is Dr. Eggman's past counterpart from another dimension. When they first met each other, they worked together as partners to dispose of their respective Sonics. The two had a great deal of mutual respect for each other, as they both referred themselves as a "gentleman genius". Due to their shared defeat at the hands of Sonic at the end of the Time Eater incident, their relationship starts to deteriorate, prompting them to argue quite frequently. Classic Eggman soon loses all respect for Eggman once he learns that he has never defeated Sonic once.

Gerald Robotnik
Eggman and Gerald Robotnik had not been known to interact with each other, although Eggman had immensely respected his grandfather, who likewise acted as the reason why he desired to become a scientist. It is also implied that his desires to form the Eggman Empire were rooted at feeling his grandfather was unfairly tried and executed. However, his respect for his grandfather was shaken somewhat after learning of Gerald Robotnik's irrational desire of destroying all life on the planet via a collision course from the Space Colony ARK due to insanity caused by grief from Maria's death. His trust was even further decreased when he learned from Black Doom that his grandfather had sold out the earth to the Black Arms in exchange for completing Project Shadow, although he regained most of his respect for his grandfather when he learned about Gerald's intention of wiping out the Black Arms with the Eclipse Cannon.

Friends/allies

 * Badniks (notably E-Series and Metal Sonic, among others)
 * Orbot
 * Cubot
 * Chaos (formerly)
 * G-merl (formerly)
 * Shadow the Hedgehog (depends on Shadow's goal)
 * Eggman Nega (occasionally)
 * Classic Eggman
 * The Time Eater
 * The Deadly Six (formerly)
 * Jackal Squad
 * Infinite

Enemies

 * Team Sonic
 * Sonic the Hedgehog (arch-enemy)
 * Miles "Tails" Prower (also a rival)
 * Knuckles the Echidna
 * Team Rose
 * Amy Rose
 * Cream the Rabbit
 * Cheese
 * Big the Cat
 * Team Dark
 * Shadow the Hedgehog
 * Rouge the Bat
 * E-123 Omega
 * Team Chaotix
 * Vector the Crocodile
 * Espio the Chameleon
 * Charmy Bee
 * Mighty the Armadillo
 * Ray the Flying Squirrel
 * Babylon Rogues
 * Jet the Hawk
 * Wave the Swallow
 * Storm the Albatross
 * Emerl
 * G-merl
 * Silver the Hedgehog
 * Marine the Raccoon
 * Blaze the Cat
 * Princess Elise
 * Eggman Nega
 * Metal Sonic 3.0
 * Biolizard
 * Black Arms
 * Black Doom
 * G.U.N.
 * Metal Sonic (sometimes)
 * The Deadly Six
 * Classic Sonic
 * Classic Tails
 * Avatar