Eggrobo

Eggrobo (エッグロボ) (originally spelled EggRobo in the manual) is an egg-shaped humanoid robot resembling Dr. Robotnik. It first appeared as an enemy in the game Sonic & Knuckles, but has since then appeared in several other main games and spin-offs.

Sonic & Knuckles
In Sonic's storyline in that game, it only appeared as a standard Badnik enemy in the Sky Sanctuary Zone, after being seen launched from the Death Egg.

It is rather more prominent in Knuckles' storyline, as the Eggrobo replaces Dr. Robotnik as the end-of-zone boss in every level up until the Hidden Palace Zone (except for Flying Battery Zone). In all of Knuckles' appearances prior to this, he had been allied with Robotnik. It's also implied that the Eggrobo in Knuckles' story is the same one that appears in Sonic's imperfect ending (if the Super Emeralds aren't collected), implying that the Eggrobo in question survived the Death Egg's destruction.

The Eggrobo also appears in cut-scenes in the game. At the beginning of the game, while Knuckles is relaxing along with some of his animal friends in the Mushroom Hill Zone, the Eggrobo drops a bomb in their midst that scares his friends away. The Eggrobo is destroyed by Mecha Sonic in the Sky Sanctuary Zone (the final level in Knuckles' storyline). The Eggrobo restrains Knuckles, allowing Mecha Sonic to charge at him, but Knuckles breaks free and Mecha Sonic destroys the Eggrobo instead.

Sonic R
Eggrobo, renamed Eggman Robo (エッグマンロボ) in the Japanese version, later appears in Sonic R as an unlockable character. It has abilities similar to Dr. Robotnik's in that game, being capable of launching missiles, though Eggrobo is a bit slow. It is unlocked by getting all of the five Sonic Tokens in the Regal Ruin course.

Like Metal Sonic, Tails Doll, and Metal Knuckles, the Eggrobo is the robotic counterpart for Dr. Robotnik. He performs almost the same although he cannot travel across water for more than three seconds before falling in which is odd because of his rocket boosters.

Sonic Adventure 2
Eggrobo also appears in Sonic Adventure 2 as a kart racing VMU Download with his own stage, and again in Sonic Adventure 2: Battle as Rouge the Bat's unlockable sub kart, obtained by getting all the emblems of Rouge's missions.

Sonic Chronicles: The Dark Brotherhood
An Eggrobo appears in Sonic Chronicles: The Dark Brotherhood as a cameo next to a Sega Genesis and a Capsule in Metropolis.

Sonic Generations
Eggrobo returns in Sonic Generations as an enemy in Sky Sanctuary, like its original appearance in Sonic & Knuckles. The game also features a different variation of Eggrobo in Act 2 which trigger missiles from above their head to home on the player. A model can be collected in the Statue Room.

Sonic & All-Stars Racing Transformed
Eggrobos make an appearance in Sonic & All-Stars Racing: Transformed, at the track Sanctuary Falls, which itself is based on a Zone from the Sonic series, Sky Sanctuary Zone from Sonic & Knuckles. In this track, Eggrobos appear as both an obstacle and as a standard appearance like he did in Sky Sanctuary Zone.

Super Smash Bros. for Nintendo 3DS
Eggrobos appears as an enemy on the 3DS-exclusive mode Smash Run in Super Smash Bros. for Nintendo 3DS. In addition to Smash run, he will also appear as a trophy.

Sonic the Comic
An army of EggRobos appeared in the Sonic & Knuckles adaptation from Fleetway Editions' Sonic the Comic. In this series, the EggRobos could be controlled directly by Robotnik from his control room aboard the Death Egg. Each model had cameras fitted into its eyes, allowing Robotnik to see everything, and a voice synthesizer allowed the doctor to communicate directly via the robots. EggRobos could also function as regular Badniks without Robotnik's direct control.

Archie Comics
EggRobos also appeared in the Sonic the Hedgehog comic series and its spin-offs published by Archie Comics. They were built by Snively Robotnik to be part of his own private army, with which he intended to move against his uncle, Doctor Robotnik, and take over Mobius himself. Although Snively referred to them as "EggRobos" in their first appearance, Antoine D'Coolette called them "Eggbots," which was the name used in subsequent appearances.

An army of Eggrobos appear in the Skull Egg Zone.

Trivia

 * In its artwork as shown in Sonic Jam, EggRobo's name is spelled Egg Robo.
 * The Eggrobo does not appear as the boss of the Flying Battery Zone in Knuckles' story. Since the sprites used to model Dr. Robotnik for that boss were different, no equivalent sprites for the Eggrobo were ever produced. Eggrobo does appear managing the Flying Battery's laser, however.
 * Similarly, there is a glitch to get Robotnik to appear as Knuckles' boss in Mushroom Hill rather than Eggrobo. In the Sonic Jam version, this was only partially fixed; Robotnik does not appear as the boss, but the graphics can instead show up as corrupted.
 * Bosses and sub-bosses in Knuckles' story (piloted by Eggrobo) are harder than those in Sonic's story (piloted by Robotnik). An example of this is the boss of Angel Island Zone, which shoots four fireballs at a time rather than two.
 * All three Sonic Advance titles have final boss robots that use title "Eggrobo"; Sonic Advance features the Super Egg Robot, Sonic Advance 2 has the Super Eggrobo Z, and Sonic Advance 3 feature the Hyper Eggrobo.
 * In Sonic Generations, the Eggrobo is the only enemy robot which shoots its own unique laser weapon. All other robot enemies with projectiles shoot a small yellow energy ball.
 * The Egg Pawns introduced in Sonic Heroes are very similar to the Eggrobos.
 * Eggrobo made a cameo on the cover of Sonic X #11.
 * The Eggrobo makes a cameo in Super Smash Bros. for Nintendo 3DS/Wii U as a trophy and as an enemy in the Smash Run mode on the 3DS version.