- For the game-series version that appeared in the Team Sonic Racing one-shot, see E-123 Omega (TSR one-shot).
E-123 Omega was built by Dr. Eggman as a heavily armed Super Badnik to serve as part of his robot armada. At some point Omega went rogue and joined Team Dark, vowing to destroy his creator and every other robot built by the doctor. (StH: #19, #25)
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. Omega was happy to oblige the hedgehog's orders as Zombots were certain to be drawn to the truck. The walking arsenal continued his defensive assault as Zombots advanced by the dozen. Rouge ordered him to divert his attacks to give Shadow some covering fire, but the robot could not let up his suppressing fire as the Zombots were closing in en masse. (StH: #1, #13, #18, #19)
With Shadow now completely infected by the Metal Virus and all the survivors loaded into the truck, Rouge fled aboard the transport as Sonic continued the fight with the Zombots. Despite seemingly being out of ammunition, Omega stayed behind with the blue blur to finish off the remaining Zombots hand-to-hand. Omega noticed Sonic's worsening infection and told him to leave so the robot could continue with his extermination unimpeded. Sonic tried to reason with the robot, telling him that he could not destroy the Zombots, but Omega was merciless and refused to spare any of them, even Shadow. Omega and the infected Ultimate Lifeform soon came to blows and Shadow managed to tear through Omega's torso and destroy his arms. Despite being impeded, Omega continued to fight as Zombots swarmed the robot and began to tear him apart piece by piece before Silver the Hedgehog and Tails intervened, the latter recovering Omega's severed head before fleeing Sunset City and heading back to Restoration HQ. Tails hooked the robot up to the computers there and began plans to build a new body for Omega, his fighting spirit still strong and eager to continue the battle against Dr. Eggman. (StH: #19, #20)
Still without a body, Omega was later evacuated from Restoration HQ by Gemerl after the site had been compromised by the Metal Virus so Tails could rebuild the robot and have him protect the uninfected. Now taking sanctuary on Angel Island with what was left of the Restoration, Omega's disembodied head ended up in the hands of Cream the Rabbit who carried the Super Badnik around with her. The two of them stumbled across Whisper the Wolf who was planning to assassinate the ousted Dr. Eggman for unleashing the Metal Virus and infecting so many, including her friend Tangle the Lemur. Cream appealed to Whisper, begging her to spare Dr. Eggman so he could help find a cure to the Metal Virus, and Omega protested that the only one allowed to eliminate Eggman was himself. Whisper saw reason in Cream's words and spared the doctor before Cream embraced her, leaving Omega as the third wheel in the tender moment. With the Deadly Six now in control of the Faceship, the Chaos Emeralds and Metal Virus production, what was left of the Restoration and its allies took off to confront each of the Zeti and retrieve the powerful gems. The Deadly Six's leader, Zavok, began a counter offensive against Angel Island, deploying Zombots, but what was left of the heroes fended them off long enough for all seven Chaos Emeralds to be brought to Sonic and Silver. Using the power of the mystical gems, the two hedgehogs became Super Sonic and Super Silver and used the power of the stolen Warp Topaz to teleport the Metal Virus off of the planet and into the sun, with many believing Sonic had sacrificed himself in order to achieve this goal. With the Restoration and the cured citizens distracted, Dr. Eggman escaped capture from the Restoration and retrieved Orbot and Cubot. The former had stolen Omega's severed head as a consolation prize for the loss of the Faceship and a helpless Omega demanded the round robot use Omega's own head to bludgeon Cubot, then for Orbot to bludgeon himself. Shadow attempted to apprehend the doctor, but with Metal Sonic's aid he escaped and Omega was now back in his old master's clutches. (StH: #22, #25, #26, #28, #29, #30)
Controlled by Eggman
With Sonic still nowhere to be found, Dr. Eggman rebuilt Omega's body with the intention of using him to crash a celebration at Spiral Hill Village. Omega was more than pleased to be fully repaired and was determined to destroy Dr. Eggman with his new body, but the scientist had made sure to lock Omega's body in paralysis and left him to float in a prison while he worked on his next project. This project turned out to be a new mecha called Giga Omega. It resembled E-123 Omega but at ten times the size and with additional weaponry scattered throughout it, a machine which Dr. Eggman dubbed the "the fiercest of party crushers!" Dr. Eggman hardwired Omega into the chassis of his latest creation to utilize his combat coding and processing power and set off for a surprise attack. As the Restoration celebrated and hoped for news of Sonic's safe return, Dr. Eggman struck, destroying several buildings and confronting the heroes of the hour. (StH: #31)
The Restoration and its allies rose to meet their foe and his new mecha, with Gemerl attempting to strike first. The mecha deployed a trap that caused Gemerl to succumb to Dr. Eggman's control, empowering the mecha further and the doctor began to open fire on the heroes. Thinking quickly, Tails and Rouge were able to find an access panel on the giant robot and release Gemerl from the doctor's control, but they also discovered Omega would be much harder to release and Tails attempted to find an ejection protocol. Seeing that the young fox had hacked into his machine, Dr. Eggman opened up his cockpit and opened fire with a laser handgun on Tails and Rouge, nearly disintegrating them. Still trapped in the mecha but with his primary systems restored, Omega's directives to destroy Dr. Eggman conflicted with his orders to destroy Eggman's enemies and caused a cascade error, disabling the mecha and its weapons and allowing the heroes to attack the giant robot, destroying one arm and hindering its legs whilst trying to free Omega. With the Restoration and their allies gaining the upper hand, Dr. Eggman began to override Omega's systems to bring him back under control and reactivate the mecha. Just as Dr. Eggman was about to destroy the heroes and Spiral Hill Village, Sonic teleported from Blaze the Cat's dimension and proceeded to wreck the bigger mecha and remove Omega as its core. Finally free and eager for vengeance, Omega used his weapons and all his ammunition to eradicate the mecha in one giant blast of ordnance, subsequently causing his damaged body to fall apart. Shortly afterward the Restoration and its allies gathered around Sonic and Omega's body for a group hug to celebrate the blue hedgehog's return. (StH: #32)
Rebuilding A Robot
A severed head once again, Omega and what was left of his body were brought to Tails's workshop by Amy Rose for a full rebuild. Rouge provided Tails with some personal files of Dr. Eggman's she had taken from the Faceship with blueprints for Omega's design, but they were unfortunately written in code and would require a cipher. Sonic and Tails decided they would head to Windmill Village to investigate an old Eggman base to try and find the cipher. Meanwhile, Rouge, Amy, Cream, Cheese and Gemerl would go to White Park Zone and meet with a collector of rare technology named Clutch to procure E-100 Series robot parts to rebuild Omega with. With Clutch being a known Chao Racer Rouge planned to enter Cheese into White Park's Chao Race tournament, pretending they were her own pet Chao upon discovering Cream was too young to participate. Going by the alias "Facet," Rouge stowed Omega's head in a suitcase before checking into the chateau and entering the race. Cheese performed well in the qualification race, earning themselves a place in the Grand Prix the next day and drawing the attention of Clutch who asked to meet with Rouge in his apartment in the penthouse suite. Keeping Omega close by in her luggage, "Facet" met with Clutch only to discover he knew of her reputation as a world-famous thief and that he wanted to make a deal; if Cheese won tomorrow's race Rouge could have whatever she wanted from his collection as long as she gave Cheese to Clutch. Once the meeting was over Omega pointed out that Cheese was not Rouge's to give and asked if she was planning to violently take Cheese from Cream, but Rouge planned to get what she wanted without ever handing over the Chao and gave Omega his own role to help in her scheme; Lay in hiding among Clutch's collection, wait until she pretended to hand over Cheese and then initiate a surprise assault using an auditory attack once she spoke the code phrase "get what's mine." Whilst in hiding, Shadow snuck inside Clutch's apartment, discovering several caged racing Chao and Omega. The two Team Dark teammates then laid in wait together until Rouge returned with Amy, Cream, Gemerl and the bargaining chip Cheese. Once the phrase was spoken, Shadow instead emerged and proceeded to knock Clutch unconscious with Omega in hand, a strategy the robot thought superior to Rouge's original plan. (StH: #33, #34, #36)
But whilst all this had been happening, another villain had been acting behind the scenes. On the night Rouge had met with Clutch, an old enemy returned seeking revenge; Dr. Starline cornered Rouge in the hallways of the chateau and hypnotized her to transmit an emergency call to Tails to land the Tornado at specific coordinates and split up with Sonic. Once Tails arrived after Clutch had been defeated, Rouge ambushed him and kidnapped him before the both of them were tied up on a roller coaster and Omega was now in Dr. Starline's clutches. Sonic and Shadow quickly realized something was wrong and went to rescue their allies, only for Dr. Starline to trigger an avalanche heading straight for the chateau. Sonic went to deal with the avalanche leaving Rouge, Tails, Shadow and Omega to fight Starline. With Omega resting at the feet of Dr. Starline in the front car of the coaster, Rouge put her original plan for Clutch into action and used the code phrase "get what's mine" to trigger an auditory attack from her robot teammate. Blaring noise sounded from Omega's head, disorienting Starline and causing him to fall from the roller coaster much to the automaton's glee. Dr. Starline kicked Omega from the car as he fell but Rouge caught her teammate before he went plummeting below. Whilst Shadow went to aid Sonic in halting the avalanche, Tails, Rouge and Omega being carried by the bat then quickly returned to the chateau to retrieve the E-100 parts they had come for. Omega urged the tourists staying in the chateau to evacuate as quickly and loudly as possible at Rouge's request before Dr. Starline made another attempt to kidnap Tails, only to be thwarted again and left to deal with the avalanche. Rouge rushed Omega on to the safety of one of the chateau's balconies and left him on the floor as she searched for Sonic and Shadow, much to the robot's chagrin. With the two hedgehogs found safe, the tourists safe and the E-100 parts secured, the group returned to Tails' workshop and Omega was fully rebuilt with the help of their new ally, Belle the Tinkerer who could read Dr. Eggman's code. Back to his old self again, Omega's first act with his new body was to take it for a "test-drive" by challenging Gemerl to a sparring match at Tails' suggestion. (StH: #33, #35, #36)
E-123 Omega has a single-minded want for revenge against Dr. Eggman, going so far as to feel entitled to his destruction. When the opportunity to destroy one of the doctor's creations arises, he takes it and attacks any and all Eggman robots with glee, no matter the circumstance. While this can cause conflict between him and his allies, he is at his best when their motives co-align. Omega will fight on even in the most overwhelming of battles and his determination can often lead to his detriment.
Omega has frequently shown a preference or even fervor for acts of violence, be they against Eggman's robots or momentary foes, and actively enthuses any plan that involves a physical altercation. Omega also seems to shy away from anything resembling amiable behavior, such as refuting being considered Sonic's "friend," objecting to calling fighting alongside Sonic "helping" him, calling verbal support being "patronized" and refusing to show mercy on Zombots that were once innocent civilians and allies.
Omega has also shown a sense of superiority towards "weak" organic beings, inherently feeling that being a robot he would remain calm in times of personal crisis (such as being decapitated) whereas organics would suffer from elevated stress. He is more than willing to take orders from Shadow and Rouge, but has enough common sense to know when to disobey a command and prioritize to achieve success.
Omega is outfitted as a battle robot with weaponry concealed in his arms that can replace his hands at will. His primary weapons are two quadruple-barreled machine guns that shoot a wide spread of bullets but more powerful ordnance that can easily destroy large Eggman mechas are also at his disposal. Omega's head is also equipped with some form of loudspeaker that can be used to louden Omega's voice or as a non-lethal weapon capable of disorienting an opponent and making them lose their balance. When his vast quantities of ammunition deplete Omega can fall back on his impressive strength that allows him to toss Zombots around like rag dolls. Omega can also rapidly rotate his torso 360 degrees, allowing him to attack droves of close range targets in melee combat.
Omega is equipped with twin jet boosters in his back that allow him to leap at great speed and distances. Omega also seems to have an independent power source located in his head that allows him to function without a body.
Aside from combat abilities, Omega is also equipped with a range of sensors that allow him to detect such things as the Metal Virus and its rate of infection.
- Main article: Giga Omega
Captured by Eggman, Omega was fitted into a larger robot body called Giga Omega, which the doctor could utilize as a mecha.
Omega is a humanoid robot with a yellow casing surrounding two red eyes for a "head," large black shoulder pauldrons with the Greek capitalized omega symbol on the front of his left shoulder, an over sized red barrel chest with a silver stripe and four vents, a black waist with a compartment exposing his inner workings surrounded by a silver, red and black pipe with arrows, two long red flaps on the sides and one shorter red flap with a substantial green section in the centre, thick black and red arms with black arrows and yellow cuffs with spikes, large four-fingered retractable gunmetal grey hands, and surprisingly skinny red, black and silver legs ending in long black "feet" with green accents between the "toes."
- Before Omega was formally introduced in the comics, he made an unofficial appearance on the retail incentive cover of Sonic the Hedgehog #9 along with Gemerl, Cream the Rabbit and Cheese, possibly meaning all four of them were meant to appear earlier into the comics' run.
- Omega has always been the last member of Team Dark to be introduced in all the comics he has been featured in. He first appeared in in the Archie Comics universe in Sonic Universe #3 whereas Shadow and Rouge debuted in issues #1 and #2 respectively. Shadow and Rouge both debuted in the main comic book in Sonic the Hedgehog #98 and Omega did not appear until #250, 4 years after his debut in Sonic Universe and almost 10 years after his first ever appearance in Sonic Heroes. Keeping the trend going, Shadow and Rouge debuted together again in IDW Publishing's Sonic the Hedgehog #5 whereas Omega did not officially appear until issue #19, along with an unofficial appearance in the Team Sonic Racing one-shot beforehand.