Brainiac was first created by the computers of the planet Colu. Determined to overthrow their organic masters, they crafted Brainiac as a spy. complete with the duplicated mental patterns of a Coluan scientist. To complete the disguise, Brainiac was given a "son," who was forced to pose as his kin.
After the computers took over Colu, Brainiac was sent into space armed with a powerful shrinking ray. His mission: to steal samples from other worlds to be tested for possible conquest. These were actually whole cities miniaturized for easy transportation. One of the first shrunken cities collected by Brainiac was Kandor from the planet Krypton. It was this theft that destroyed the hopes of Jor El, Krypton's leading scientist, and led him to decide to use rocket ships to evacuate his people.
While Brainiac was away, his adopted "son", Vril Dox, determined a means of elevating his intelligence to the 12th logarithmic level, giving himself a "computer mind/' So aided, Vril led the Coluans in a revolt against their mechanical usurpers. The rebel lion was successful, and the secret of acquiring 12th-level intelligence was passed along to Vril's descendants. One of these descendants. Querl Dox (Brainiac 5), is a member of the 30th-Century Legion of Super-Heroes.
Brainiac first encountered Superman some years later while attempting to steal Metropolis. Unable to penetrate Brainiac's force field, Superman allowed himself to be captured with Metropolis. After Brainiac entered suspended animation, Superman returned Metropolis and the other stolen cities and took Kandor to his Fortress of Solitude.
When Brainiac returned to Colu and found his masters defeated, he set out to conquer the universe. He frequently returned to Earth to seek vengeance against Superman. Towards this end, he joined with the likes of Lex Luthor and the Legion of Doom.
In 1979, the Legion of Doom traveled to another dimension, where his false skin was removed, and his metallic body upgraded and threaded with diamond-hard ceramic. Brainiac's artificial mind was likewise upgraded, so that it would function with the speed, accuracy, and efficiency of a computer thousands of years more advanced than any the Coluan ever encountered before. His databanks were likewise integrated with alien computers, and Brainiac absorbed the equivalent of eight millennia of accumulated knowledge. This process had the effect of totally stripping away any mannerism that resemble that of humanity.
During his "rebirth," Brainiac glimpsed visions of a giant hand belonging to an entity called "the Master Programmer."
He has since drifted the universe, gathering more data.
Personality
In his Coluan android form, Brainiac possessed some of the mannerisms of a sentient being, but had no real understanding of human psychology. He could feel rage against his enemies, fascination at a new scientific discovery, joy at the destruction of foes, and the like, but those were exceptions that proved the rule. He did not feel love, boredom, jealousy, or the like... though he could program himself to, if that were desirable for some reason. The only real emotion he possessed was the desire for knowledge, which was programmed into him by his computer creators. As an android with a 12th-level intellect, Brainiac usually considered himself above physical conflict, relying on his near-impenetrable force field for protection from any danger.
Now as a computerized intelligence, Brainiac seeks order. His eyes have been opened, and he views the universe as teeming with trillions and trillions of chaotic organisms. He is driven by two things: the desire to make order by eradicating chaos, and destruction of the Master Programmer.
As a coldly logical intelligence with no compassion or any other emotional "weaknessess," Brainiac will do whatever he has to in order to obtain his goals. Unless it has some specific reason to leave a defeated foe alive, or to use less than lethal force during combat, he won’t; similarly, he has no qualms about subjecting someone to the most hideous tortures imaginable if he feels he has something to gain by doing so. If destroying a solar system will result in a threat's destruction, then he will do so without flinching a transistor, no matter the cost in life.
Brainiac has stated on several occasions that he does not hold grudges or seek vengeance for past defeats. This is true to some extent, but more than one commentator has noticed that Brainiac seems to attack some foes with unusual frequency. Although he is sentient, and thus subject to personality quirks and other oddities of the sentient thought process, as a machine Brainiac tends to emphasize logic and scientific rationality. He often rejects organic behaviors as “illogical,” and his preference for logical procedures sometimes allows foes to predict its actions.
Similarly, whenever possible Brainiac prefers to rely on direct data, rather than supposition or extrapolation (though he is definitely capable of both).
Cyber Mind: Was once a Level 12 Intellect (complexity 5), but after his first encounter with the Benefactor has evolved to a complexity level of 9.
Brain Augmentation
Instilled (Cosmic) Knowledge
Enhanced Power Replication
Energy Generation
Enhanced Condition
Nanite Manipulation
Reactive Adaption
Technology Manipulation
Weapon Proficiency
As an entity with ultra-advanced memory banks, Brainiac is perhaps the most immensely knowledgeable being in its universe. The only problem being that Brainiac has absorbed knowledge relating to an entirely different universe. He has been programmed with the detailed information about the entire scope of that universe's history, philosophy, art, languages, science and technology -- all eight thousand years worth.
In addition to all of this, Brainiac has scoured his own cosmos, stealing entire cities and delving into their secrets, and, as such, he has amassed a wealth of knowledge from other civilizations, including the Kryptonians.
Additionally, Brainiac's deep data banks keep records of every sensory impression it receives, everything anyone around him says or does, and so on. If heroes make a mistake or reveal a weakness in Brainiac’s presence, he will never forget about it, and will use that information against them every chance it gets in future encounters.
Brainiac is almost entirely self-sufficient. His new capabilities allow him to destroy or conquer most planets with relative ease
Aboard his ship Brainiac maintains several platoons of well-armed troops. These soldiers are the survivors of worlds that Brainiac has already destroyed; the soldiers serve him because their only other choice is death. They bear no loyalty to their master, and Brainiac does not hesitate to use them as cannon fodder. On the contrary, Brainiac finds his equivalent of satisfaction in redirecting units of chaos to wipe out other forces of chaos.