Untold eons ago, an long hunted and dying out race created the Omegex to safe guard their survival. The Omegex was biological machine similar to the Destroyer of Asgard but with a deadly power source, the life force of those it killed. The Omegex sought out its enemies and wiped them out and absorbed their life forces but it worked too well. Soon the Omegex main program became to exterminate any race that was a threat to its creators and hence it scourged the cosmos wiping out enemies left to right. Eventually it came to the Milky Way Galaxy and attacked the Watchers, whhich the Omegex saw a true threat due to their observations of the cosmos. Uatu and other members of the Watchers were able to repel the Omegex and it left the galaxy.
Major Story Arc
After being repelled by the Watchers Omegex keep searching for their energy sigantures but they were able to hide it from Omegex somehow. But then it picked up a piece of Uatu energy. When the Red Hulk was able to punch Uatu a piece of the Watcher's energy transferred to him, and this was what Omegex had sensed.
Omegex made his way back to the Milky Way and directly to earth. When it arrived the Red Hulk signature disappeared, he was taken to another time line by Uravo. When Omegex couldn't find the Red Hulks energy he left Earth but he returned when the Red Hulk returned. This time Omegex and the Red Hulk fought and when it looked like the Omegex would win the Black Fog stepped in and Zero/One phased the Red Hulk out of time again.
This time Omegex was able to trace where the Red Hulk went and when he returned Omegex was waiting for him. Omegex was able to beat the Red Hulk within an inch of his life, but right before striking the final blow the Red Hulk changed back into Ross and the Omegex lost the Red Hulk's signature again this time it deduced that the Red Hulk was dead and its mission complete.
Since Ross' energy signature was different than in his transformed state, Omegex read it as being that his assigned target was destroyed. It then disintegrated and vanished into millions of dust-like particles, effectively dying now that its main objective was "accomplished".