Michael Korvac was born in 2997 and was a computer technician on the moon when the alien invaders known as the Badoon conquered the Earth. Seening an opportunity present itself, Korvac collaborated with the Badoon, betraying the people of Earth. Later on, as punishment for falling asleep at work, the Badoon grafted Korvac's upper body to a machine.
The cosmic being known as the Grandmaster captured Korvac and brought him to the present as a pawn in a game involving Doctor Strange and the Defenders. Korvac spends his time studying the Grandmaster's power and uses the new abilities gained from his study when he returns to his own time. He then kills his Badoon masters and attempts to destroy the Earth's Sun.
The heroes of that time, the Guardians of the Galaxy, manage to defeat Korvac (with the help of a time-traveling Thor), but Korvac escapes to his past (our present) and discovers the base of the world-eating Galactus. While there, Korvac gains great cosmic power, and recreates himself as a man named...Michael. The Guardians travel back through time to capture Korvac. In the meantime, the Collector (brother to the Grandmaster) realizes that Korvac is a threat, so the Collector transforms his daughter, Carina, into a being powerful enough to combat Korvac. However, his daughter instead falls in love with Korvac/Michael, and the two go to Earth and begin living a quiet live in Queens, New York.
The Collector then tries to capture the Avengers (and the Guardians) in an attempt to protect them from Korvac, but when Korvac finds out about his plot, he kills the Collector.
The Avengers travel to Queens where they discover Michael and Carina living quietly. After they confirm that he is, in fact, Korvac, the Avengers wage a tremendous battle that leaves almost all of the Avengers dead. Finally, though, Captain America and Wonder Man weaken him enough so that the Vision, Iron Man, Thor and the Guardian Starhawk could really hurt him. During this battle, Michael realizes that Carina is losing her faith in him (seeing a guy kill a whole bunch of superheroes will do that to you), so he decides to kill himself. Carina goes nuts and attacks the Avengers, as well, but Thor manages to kill her.
Michael's last act before dying is to resurrect all the dead heroes.
The storyline was written by Jim Shooter and David Michelinie, and was drawn by George Perez and David Wenzel. It took place over "Avengers" #167-177.