Dr. Eggman as seen on Sonic X
In Sonic the Hedgehog video games, Doctor Eggman (in modern-day and Japanese versions), or Doctor Ivo Robotnik (early United States and European versions), is the archnemesis of Sonic the Hedgehog. His character designer is Naoto Ohshima.
Dr. Eggman, the grandson of Professor Gerald Robotnik, is an evil genius with an I.Q. of 300 and a very childish demeanor. He tries to take over the world by enslaving the population inside robots to serve his every whim. Of course, Sonic and his friends are always there to stop him.
He has built countless airships, such as the Egg Carrier, and a moon-sized space station called the Death Egg. He has also built countless robots, a great deal of which resemble either him or his longtime rival, Sonic.
In most video games, the main villain is the final boss fought by the player. Eggman, in contrast, appears as the boss of every level in most of the Sonic games, in a different machine each time.
Best of British
In UK publications - first the book, Stay Sonic, and later the enduring Sonic the Comic, as well as some other UK novels - Doctor Robotnik (as he was consistently called, even when the video games switched to using the "Eggman" name) had a particularly different origin to anything from any other country. He is inextricably bound to Sonic by this origin. Originally, he was not Doctor Ivo Robotnik, but was Doctor Ovi Kintobor, a kindly scientist from Earth who embarked on a one-man science exploration of space, but wound up stranding himself on Mobius. The planet was a world of peace, and so he vowed to eradciate even the tiniest traces of negative energy from it. Using a machine he named the Retro-Orbital Chaos Compressor (ROCC), formed of many purifying golden rings, he slowly gathered all the negative energy on Mobius. Requiring a container for chaotic energy, Kintobor discovered emeralds that served the job very well, locating six of them. It was then that a brown hedgehog named Sonic came tumbling into his lab. Kintobor quickly became friends with Sonic, and helped him to advance his speed - while testing a new invention of Kintobor's termed "Power Sneakers," Sonic ran so fast that he broke the sound barrier, and the shockwaves fused his quills and tempered his body cobalt blue. (In the UK comics, this part was modified slightly so that the sneakers were invented after Sonic turned blue.) Sonic used his new speed to help search for the seventh and final emerald, which was required to stabilise the energy transfer. Their efforts were in vain, but Kintobor eventually apparently discovered a way to complete the transfer without the seventh emerald. Before the process was initiated, the pair decided to have lunch, but going to the fridge, they found only one rotten egg. With it in his hand, muttering about it, Kintobor went back to the ROCC... and tripped on a cable, falling over and slamming his hand into the machine's control panel. The ROCC exploded, bathing Kintobor - and the egg - in chaos energy, and scattering the golden rings that comprised it across the planet. As the smoke cleared, Sonic made a terrifying discovery - the chaos energy had transformed Kintobor, along with the rotten egg he had been holding. Now, he was no longer Ovi Kintobor - now, he was Ivo Robotnik.
And the rest is history.
The doctor's Eggman-shaped robots have evolved throughout the series, first appearing in Sonic & Knuckles as the simple but numerous Egg-Bots or Egg-Robos. Soon after, Eggman followed up with more lethal incarnations that could think for themselves — the E-series. Notable E-series robots include E-101 Beta, E-102 Gamma, and E-123 Omega.
Gamma, who was forced by Eggman to defeat his brother Beta, gained a conscience after an encounter with Amy Rose, and decided to free the animals imprisoned in all of Eggman's robots, including the ones inside the E-series. Beta, on the other hand, never got over his first defeat at the hands of Gamma, and actively reengineered and modified himself to finally destroy Gamma once and for all. Gamma, having destroyed all the other robots and freed the animals inside, went on to have a final showdown with Beta, going into battle with one thought in mind: he too has an animal imprisoned inside.
Omega, on the other hand, is a prototype robot which Eggman quickly dumped after he began work on the next line of robots, the E-2000. Infuriated by this, Omega joined Team Dark with Shadow the Hedgehog and Rouge the Bat in Sonic Heroes.
The Death Egg was Doctor Robotnik/Eggman's space station in Sonic and Knuckles. It was moon-shaped, and built in the image of Eggman's face. (This idea was later recycled for the Colony ARK.)
The Death Egg was powered by Chaos Emeralds.
The Death Egg may be a parody of the Death Star found in Star Wars.
The SatAM version of Robotnik
Robotnik, aside from the huge mechas and robots he builds in his likeness, also seems to enjoy trying to make robot Sonic the Hedgehog knock-offs to pit against his rival. His first attempt was Silver Sonic, a dismal failure due to the fact that it was the total opposite of the original — slow, unwieldy, big, and stupid. Silver Sonic II, or Mecha Sonic, was a much sleeker and more aggressive design, and it was also faster and able to fly. Sonic thought he had defeated it in the Sky Sanctuary of Angel Island, but it later reappeared and fought Knuckles. Mecha Sonic got hold of the Master Emerald and attacked Knuckles as Super Mecha Sonic, but, not being able to absorb the Emerald into its being, needed to constantly recharge his power. Knuckles soon managed to defeat it during these recharge lapses.
Eggman's most successful and persistent Sonic copy to date is Metal Sonic. Metal Sonic, after his first defeat at the hands of Sonic, went on to harass the Chaotix, where he was able to turn into a huge, red, Godzilla-sized version of himself via the Chaos Rings and wreak havoc for a while, until he was defeated once again. Since then, he's been seen around participating in any kind of racing or fighting Sonic joins in, in hopes of defeating him one day. In Sonic Heroes, Metal Sonic seems to impersonate Eggman in an attempt to copy the Sonic Heroes' DNA and finally put an end to their rivalry, once and for all.
In the Sonic Adventure games, Eggman became increasingly used as comic relief.
Eggman has been the primary antagonist in all of Sonic's incarnations. All have a different voice: