1960s Ego once told Thor that his existence was the result of a scientist merging with a planet when that planet's sun went nova. Inside the Black Galaxy, Ego's ambitions turn towards conquest. He starts absorbing space vessels and other planets to gather strength. This behavior attracted the attention of the
Rigellian Colonizers, who feared that the nearby Ego would consume their homeworld. They asked the help of the thunder god
Thor, to defeat Ego. Accompanied by a Rigellian
Recorder, Thor encountered Ego, who forced him into his body and created Anti-body minions to attack him, intending to test their strength and planning to send them across the universe to conquer other worlds. Thor fought them off and stunned Ego with a powerful storm. Feeling humiliated by his defeat, Ego vowed never to leave the Black Galaxy. Several months later, a weakened
Galactus invaded Ego's space and sought to replenish his energy by consuming Ego. Thor aided Ego in battling Galactus and drove Galactus off. In gratitude, Ego takes in the Wanderers, a group of various alien races whose planets had been the first to be devoured by Galactus billions of years ago.
1970s The Rigellian
Tana Nile took a sample of Ego to fertilize sterile worlds being considered for habitation. However, this drives Ego insane, and it soon gives in to its primordial urges and absorbs the Wanderers, which causes Thor to side with a returning Galactus. Assisted by
Hercules and
Firelord, Thor holds Ego off until Galactus attaches a massive starship engine to Ego's south pole, which drives him constantly through space and prevents him from being a threat to other planets and populated sections of the universe.
1980s Years later, Ego gains control of the engine and tracks Galactus to Earth, seeking vengeance. Unable to locate him, Ego attacks Earth. He causes massive destruction, which is later undone by a reality-altering mutant. The
Fantastic Four attempted to defeat Ego by removing the power cell from one of the attached propulsion engines, which the
Thing attempts to throw into Ego's "brain". In response, an angered Ego attempts to counter with his remaining engines but is propelled into the Sun. Ego, however, slowly reforms from a few surviving particles and repairs the propulsion unit. Ego later joins the
Elders of the Universe in a plan to destroy Galactus. Ego is sidelined before the confrontation when he is defeated by the
Silver Surfer. Ego subsequently captures the Silver Surfer and attempts to consume his energies. A sentient bio-verse, initially described as "Super-Ego", then begins to consume Ego, but Ego eventually escapes.
2000s Driven mad by the
Supreme Intelligence, Ego lashes out at other planets, destroying them while trying to 'awaken' others like itself, until it is defeated in a battle with
Professor X, the Silver Surfer and
Cadre K. Ego is subsequently captured and sent to Earth as an "infant" in spore form. As Ego grows, it begins to consume the Earth, with the Supreme Intelligence intending to allow it to grow so that the
Kree can take control of Ego and use it as a weapon against the rest of the universe.
Quasar absorbs it to prevent this. When Quasar dies during the Annihilation war, Ego was released back into the Universe, only to be approached by the Worldmind to join the new
Nova Corps. Ego supplants Worldmind and brainwashes the Corps. When Ego resurfaces his personality on his body, Nova stargates
Mindless Ones into Ego's brain, injuring him and forcing him to stargate away.
2010s Ego learns he was one of two entities created by the
Stranger for a science experiment, and that his brother
Alter-Ego has been held in captivity by the
Collector since birth. When Ego is infested by large insect-like creatures he hires
Rocket Raccoon to eradicate them.
Galactus, changed into the Life-Bringer by the Ultimates, encounters Ego after regaining his strength after a battle with the new universal construct Lagos. Ego attacks Galactus as he journeys to his inner brain at the center of the planet, however loses control of his constructs, which realize that Galactus is not a threat. Ego then reveals that before his creation by the
Stranger, his consciousness was that of a man named Egros, similar to Galactus' former self Galan. After formally meeting one another and putting aside their past animosities, Galactus uses his Life-Bringer abilities to form a body for the rest of Ego, who now calls himself Ego-Prime. Ego-Prime participated in the final battle against the First Firmament's forces. Following the First Firmament's defeat, Ego returned to his normal antics, detaching his new body and returning to his planetoid form. Additionally, Ego is revealed to have a living moon named Illa, who is his daughter. Due to Illa orbiting on Ego's far side, the two rarely see one another until
Moon Girl enables them to.
2020s Ego later allows a
Skrull cult called the Brethren of the Forgotten Flame to take shelter in its surface. However, the
Guardians of the Galaxy discover that the cult is committing a mass sacrifice, encasing Ego in a dark shell. After breaking free of the shell, Ego is possessed by the cult's object of worship,
Dormammu. ==Powers and abilities==