Omega was the most powerful member of the Thanosi. The Thanosi were powerful android, clone and mystical doppelgangers created by the mad Titan, Thanos. Realizing that he had made countless enemies and that living was a danger in itself, Thanos felt the need to create trusted allies. He used the DNA of several probable foes and possible comrades. Thanos revealed to Gamora that he had begun dabbling in the occult about three centuries before her birth and that his first test was Ka-Zar and a low-level model that proved needlessly destructive. Thanos admitted to setting a higher-level creation against the Asgardian Thor and it ran completely out of control causing the death of millions. Thanos realized that the most disturbing flaw to his creation was there intellectual deficiency, which usually ended with them settling for the most destructive answer to any problem. He deemed them to dangerous and unpredictable to use even under supervision, thus they were scheduled for recycling. However, unbeknownst to Thanos, the being known as Atlez, infiltrated his laboratory and activated five doppelgangers and Omega was among the five. All five were programmed with Thanos’ nihilistic personality phase, which meant that their greatest desire was to end all life in the universe.
According to Thanos Omega was a mistake from the start. He was a model that he would have never willingly set lose upon the universe. However he was set lose by Atlez, who gave the five Thonsi, one line of data that activated them. The line read that Adam Warlock was the key to Oblivion. Omega began ingesting planets within the Kree Empire, to satisfy his insatiable hunger. Millions of souls perished with their homes. The sacrifice of the Kree lives meant nothing to Omega, because he had only one ultimate goal to unlock Oblivion. Omega and his brothers actions upset both Eternity and Infinity eponymous personifications of all time and space. The two entities were considering turning the universe inside-out, in order to save the universe form the Thanosi's destructive plan. Thanos and Gamora searched the galaxy in search of Omega, while they tried to devise a plan to take down a being with the combined might of both Thanos and Galactus. Omega was enroute to the home of the young Earth girl known as Atleza Langunn. Omega craved the death of Atleza, who had been recently identified as the new anchor of the universe. The death of the young child would usher in the Oblivion of the universe. Preparing for the eventual battle against Omega, Thanos teleported the home of the young girl to a place in space were the casualty level would be low, protecting the Earth from possible destruction.
Omega battled the combined forces of Thanos, Adam Warlock, Doctor Strange, Captain Marvel, Moondragon, Gamora, Pip the Troll, and Spider-Man. Omega appeared to outmatch these combatants until Thanos persuaded Warlock to embrace the fighting spirit of the Thanosi Warrior, which he had summoned into his Soul Gem. The Karmic blast from the Soul Gem was strong enough to separate Omega from his space craft. While in battle Thanos revealed that Omega was activated before all of his deficiencies had not been worked out, Captain Marvel noticed that the being suffered from what was call reaction retardation, although he as able to broadcast a solid wall of force. Omega’s ship was destroyed and he was teleported to a planet in space that Thanos had surrounded by an armada of remote controlled battleships. The ships destroyed the planet giving Omega more power than he could process at one time, which led to his apparent destruction.