*E-123 Omega is the last of the E-100 Series line of robots created by Dr. Ivo "Eggman" Robotnik. Some time ago he went rogue from his creator and vowed to destroy him and all of his other robots.

Omega has since become a member of Team Dark and as such is a staunch ally of Shadow the Hedgehog and Rouge the Bat.

E-123 Omega was built by Dr. Eggman as a heavily armed Super Badnik to serve as part of his robot army. At some point, Omega went rogue and joined Team Dark, vowing to destroy his creator and every other robot built by the doctor.

Following Dr. Eggman's return after his defeat at the hands of the Resistance, the doctor hatched a new plan to create a robot army by infecting the organic flora and fauna of the world with the Metal Virus. Using his Faceship to disperse his new concoction, Dr. Eggman eventually set his sights on Sunset City and Team Dark aided in evacuating the local residents.

Omega wasted no time in unleashing his arsenal at the transforming citizens, despite the protests of Sonic the Hedgehog, but due to the victims of the virus being able to self-repair, Omega's efforts merely delayed them instead of destroyed them.

Not one to be discouraged, Omega continued with his ineffective extermination as Sonic and Rouge organised the survivors into the Grand Gold Flicky Hotel. Running low on ammunition and quickly getting overwhelmed as Zombots advanced on both sides of Omega, Sonic showed up just in time to split the threat as Omega began using the bodies of the Zombots to create a barrier wall. With Shadow finally on the scene with transport for the survivors, the Ultimate Lifeform ordered Omega to safeguard the truck as he went on the offensive.*