Doppelganger is an evil, near-mindless duplicate of Spider-Man that was created by Magus during the battle known as the Infinity War. The eight-limbed creature was one of many doppelgängers created by Magus during this conflict. The Doppelganger possesses Spider-Man's strength, speed, wall-climbing abilities, and spider-sense, and also has six arms, claws, fangs, and the ability to produce its own razor-edged webbing. It acts like an animal, and growls and hisses rather than speaking.
The Doppelganger began life as a living fractal, a geometric pattern in the Dimension of Manifestations, able to assume the forms and attributes of any being, real or abstract. When a mysterious Magus sets out to obtain the vast power of the Infinity Gauntlet, he contracts the ruling fractal, Prime Manifester Anthropomorpho, to transform several young fractals into monstrous versions of Earth's super heroes; the Doppelganger is one such creation, based upon Spider-Man. It and its brethren are sent to Earth to attack the heroes in the so-called Infinity War. The Doppelganger interrupts a fight between Spider-Man and Hobgoblin, who impales the creature upon a fence. Though most of the fractal doubles were completely destroyed upon being defeated, the Doppelganger is retrieved by the demonic Demogoblin, who infuses it with supernatural energy, enabling it to remain in the Earth dimension even following Magus' defeat. Demogoblin directs the Doppelganger in a grudge against Hobgoblin, whom the altruistic Spider-Man protects. The foursome's fight joins another battle where the supernatural Ghost Rider and Blaze are fighting a group of demonic Deathspawn and Spider-Man's murderous nemesis Venom. Both the Doppelganger and Demogoblin are subsequently pulled underground by the Deathspawn, with two Deathspawn briefly taking up silent residence within the Doppelganger's body.
After being separated from the Demogoblin, the disoriented Doppelganger wanders around New York for some time. By the beginning of the Maximum Carnage storyline, it is attacked by the psychotic Carnage, who mistakes the creature as his mortal enemy, Spider-Man. However, Carnage's companion, the equally insane Shriek, takes a liking to the Doppelganger, and the deranged couple introduces their new "son" to the "pleasure" of random murder. During their spree, the three are joined by Demogoblin and Carrion; they also fight Spider-Man, Black Cat, Cloak and Dagger, Venom, Firestar, Morbius, and others. The Doppelganger becomes devoted to Shriek; when Carnage attacks her for rebellious behavior, it springs to her defense, but Carnage guts it and kicks it to the street several stories below, supposedly killing it. Carnage and the others were defeated shortly afterwards.
Doppelganger reappears, with a new physical configuration, trying to rescue Shriek (who he is implied to have been covertly visiting at Ravencroft) from an armored truck, but he is shot in half in the process. Doppelganger is collected by Hall Industries, revives on the autopsy table, and joins Shriek in causing havoc in New York. When Doppelganger attempts to save Shriek from the new symbiote Scorn, he is nonchalantly knocked aside, and forced to flee with Carnage. When Carnage overtakes a Colorado town, the Mercury Team is able to locate him by attacking and following Doppelganger, who is referred to as "that creepy thing that looks like Spider-Man".