Death Egg Robot

The Death Egg Robot (デスエッグロボ) is the final boss of Sonic the Hedgehog 2, with an upgraded version also serving as the final boss of Sonic the Hedgehog 4: Episode I. It appears as the second boss of the Death Egg Zone in the former, fought immediately after Mecha Sonic. It looks much like a giant robotic Dr. Robotnik, but is in fact a suit piloted by the doctor himself. It is very difficult to defeat as there are no rings in the entire stage. This boss is repeated in Sonic Generations, but not as the final boss and as such is pitched at a lower difficulty.

The mech is also fought as the final boss of Sonic the Hedgehog 4: Episode I. This variation is similar, with a noticeable paint job to reflect the modern Eggman design, but takes more hits to defeat, although there are rings available in the stage.

Sonic the Hedgehog 2
After boarding the eponymous space station and beating Mecha Sonic, Sonic (or Tails, depending on who the player chooses) chases after Dr. Robotnik, who escapes into his Death Egg Robot on the large hall. When Dr. Robotnik reaches and jumps inside of this battle armor, it then starts moving very slowly towards the player. The player must jump and hit the body to damage it, a difficult task, because if the attack is timed wrong, the player might touch one of the hands and lose a life.

After a while, the robot will fly off screen and a lock-on target will appear and follow the player. Soon, the lock-on will start flashing and the Death Egg Robot will slam down, trying to squash the player. If the player manages to get behind it, Dr. Robotnik will launch a pair of spherical mines from the top of the mech's jetpack, almost certainly killing them. When it comes down, its hands will fire, attempting to hit the player. This battle mech is tough, as it takes 12 hits to destroy it completely. Repeating the process, the mech will break down and explosions will follow the player as Sonic (or Tails) will throw himself out of the Death Egg into space.

In Knuckles the Echidna in Sonic the Hedgehog 2, the Death Egg Robot is the hardest boss in the game with Knuckles. This is due to Knuckles' jump height being too low to hit it normally, so the player must do it as he lands, because as it crouches, it is low enough for Knuckles to jump and hit him.

Ending
If the player gets all the Chaos Emeralds and finishes as Sonic, a storybook-like ending will play with Tails and the small animals watching the Death Egg explode. Tails then gets into the Tornado so he can find Sonic in free fall. While flying, he spots Sonic, who activated his Super State sometime after escaping the Death Egg. The two then fly away and fly toward the screen. If the player fails to get the Emeralds, the ending is the same, but Sonic will land on the wings of the Tornado and will jump towards the screen.

In the iOS version of the complete ending, the Death Egg Robot is briefly seen in the end screen, completely ruined, while Dr. Eggman is throwing a fit, as Knuckles watches in the bushes.

Sonic the Hedgehog 4: Episode I
The Death Egg Robot returns as the final boss of the E.G.G. Station Zone in Sonic the Hedgehog 4: Episode I. It is the upgrade of the original Death Egg Robot, featuring a slight redesign and new color scheme. It first repeats its pattern, as moving slowly, tries to fall down on player's neck and fire its arms. It does not include small bombs when the player is behind of it. It is, in essence, the same mech from Sonic the Hedgehog 2, but like the other bosses in the game, it shows new attack patterns after being heavily damaged.

After sixteen hits it becomes surrounded by electricity, making it impossible to damage directly. It also appears to malfunction, randomly leaping across the field both forward and backward, firing its rocket hands at a much faster pace. To damage it, Sonic must knock its severed arms back into it when one flies off and floats back down. This disables its electrical field long enough to strike its body. After about six hits, the mech starts shooting lasers at Sonic from a compartment in its head. There are two types of lasers, the first being pink bullets commonly used by many other enemies within the levels and second a powerful beam that shoots along the ground (this attack is absent from the iOS versions).

On its last hit, the machine will fly up and attempt to destroy the space station around it to drop Sonic into the vacuum of space. It must be hit before the floor falls apart to clear the game. If the player doesn't hit the robot in time, the Mech will break the floor causing you to fall and lose a life. This move is similar to the Egg Viper's last attempt to defeat Sonic.

Sonic Generations
 In the console versions of Sonic Generations, the Death Egg Robot appears as the main boss of the Classic Era. Classic Sonic fights it aboard the Death Egg, after Sky Sanctuary, representing Sonic the Hedgehog 2.

Additionally, this version is much taller than its Genesis counterpart, and features a sturdier chassis that cannot be damaged by Classic Sonic's normal attacks (apart from several weak spots located in its posterior and head). Wheels also appear to be installed in its feet, giving it a higher level of maneuverability. The antennae seen on the head of the original model are also absent and the arms appear to have been redesigned to launch telescopically and are also much bulkier to allow for the rotary spikes on their ends. Even with these attachments, the boss fight is much easier than it was in Sonic the Hedgehog 2, due to the presence of rings.

Later in the game, this boss makes a cameo in Speed Highway and City Escape. It shows up on a poster for Chao in Space: The Search for Tikal.

Adventures of Sonic the Hedgehog
The Death Egg Robot appears in the episode Momma Robotnik's Birthday. It appears where Momma Robotnik shows a video to Tails about Robotnik. In the video, he is on the robot, but falls down when the robot moves. Curiously, the Death Egg Robot is actually a robot instead of one with Eggman in it.

Sonic the Comic
The Death Egg Robot (referred to only as Robotnik's "deadly battle armour") appeared in flashback in Sonic the Comic #27, "Part 2: A Tale of Tails". The main events of Sonic the Comic take place after Sonic 2, and in the story in question, the Death Egg Robot is revealed to have played precisely the same role as in the game: Sonic fought Robotnik aboard the Death Egg (with Robotnik in the Death Egg robot) in order to prevent the satellite's operation.

Archie Comics
Although the Death Egg Robot itself would later appear, Dr. Robotnik did wear a powered suit of body armor called the Eggs-O-Skeleton in Sonic Quest #3, "Over Easy", as part of Archie's original adaptation of the Death Egg saga.

The real Death Egg Robot appeared in issue #229, where it was known as the Egg Destroyer Battlesuit. It was giant battle robot built and used by Dr. Eggman during Operation: Clean Sweep to be Eggman's last defense against Sonic. After Sonic boarded the Death Egg Mark 2, Eggman piloted the machine and almost killed him with it after overwhelming the hedgehog with its weapons and overall strength. Once Sonic turned into Super Sonic using the energy of the Chaos Emerald flowing through a power cord though, Eggman found his mech to be completely outmatched and unable to harm the hedgehog with any of its weapons. The robot was totaled shortly after.

Trivia

 * While not exactly the same machine, Robotnik uses the robotic armor suit to escape at The Doomsday Zone in Sonic & Knuckles. After the player destroys the robot's blue rocket armor, Robotnik manages to yet take flight now with the robotic armor suit, that is heavily similar to Death Egg Robot.
 * The Sonic the Hedgehog 2 version of the Death Egg Robot bears a strong resemblance to the ATM-09-ST Scopedog from the 1983 mecha anime Armored Trooper VOTOMS.