Zzzax was the product of an accident that occurred at a Consolidated Edison nuclear power plant when a group of heavily armed terrorists attempted to shut down the power for New York City. The explosion that their stray gunfire caused started a chain reaction in the atomic reactor, creating a psionically charged electromagnetic field of humanoid form. As the electromagnetic form grew, it incinerated those people who stood in its way, absorbing the electro-psionic fields generated by their brains, and thus acquired a human intelligence. As it began to think and become aware of its surroundings, it developed rudimentary speech and named itself Zzzax in imitation of the electrostatic "crackle" it made when it moved. As it killed more human beings, it grew more intelligent; consequently it began a campaign of murder and destruction in order to increase its intelligence further. Zzzax clashed with both the Hulk and Hawkeye. Zzzax short-circuited and its constituent field dissipated when Hawkeye shot an arrow attached to a long conducting wire through Zzzax into the East River.
Zzzax reformed months later as a result of a mistake in a scientific experiment performed by Soul Star Research, a group of three scientists, Massachusetts Institute of Technology graduates Mark Revel, Stan Landers, and Alexandria Knox, who developed a mechanism that was allegedly capable of collecting and recording the scattered electrical brain waves of any human being who had ever existed. When first used, the machine made contact with an unusually intense field of electro-psionic energy in the upper stratosphere, which was the residue of Zzzax. The collected electrical impulses formed a field of sufficient energy to explode the machine's titanium casing, and Zzzax reformed. Stan Landers was killed by Zzzax as the creature absorbed his electro-psionic energy. As a result of this absorption, Zzzax found itself influenced by Landers' intense love for his colleague Alexandria Knox, and abducted her. Once again Zzzax battled the Hulk. Soul Star's Mark Revel short-circuited and dissipated Zzzax by shooting a sufficient length of copper wire through it from a helicopter and then flying the helicopter, which still held one end of the wire, directly into a thunderstorm in which the helicopter was struck by lightning.
Later, when Stark International constructed a laboratory for Dr. Bruce Banner (who was also the Hulk), the company made the mistake of purchasing a central power core from the now-defunct Soul Star Research. When the generator was hooked up, a sudden surge of electromagnetic discharge brought Zzzax back into existence. The mechanics of this reemergence of Zzzax have never adequately been explained; presumably a portion of Zzzax's electro-psionic field lay dormant in this device which powered Soul Star's previous experiment. After a brief battle the Hulk, who at that point retained Bruce Banner's intelligence when in his superhumanly strong form, ran power cables through Zzzax which were connected to a generator which drew its power from stellar and quasi-stellar sources. The Hulk reversed the generator's polarity, sending Zzzax out into space. Zzzax reappeared, emerging from high voltage lines connected to a California nuclear power plant. Exactly how Zzzax reformed this time is unknown, but its recreation is probably at least in part the work of Franklin Hall, who sought Zzzax as an ally. On Hawkeye's suggestion Wonder Man uprooted a water main, which the latter then used to fire a torrent of water at Zzzax. Hawkeye then shot an arrow carrying a conducting wire through Zzzax into the water upon which Zzzax was standing. As a result Zzzax was grounded and its field was disrupted. Somehow Zzzax was imprisoned by S.H.I.E.L.D. (Earth-616) soon after Hawkeye and Wonder Man defeated it. SHIELD kept Zzzax, which was still in humanoid form, confined within a large insulated vacuum tube, and then transferred it into another such tube at Gamma Base, New Mexico. There former General "Thunderbolt" Ross, who was obsessed with a desire to destroy the Hulk, submitted to a SHIELD experiment to transform him into a superhuman being by infusing some of Zzzax's "living electricity" into Ross's body. But the experiment went awry, and Ross's psychic energy--his mind, in effect--was absorbed by Zzzax, and Zzzax broke free. But, strangely, Ross's mind, perhaps because of the strength of its hatred for the Hulk, took control of Zzzax, submerging Zzzax's own personality. Meanwhile, Ross' original physical body remained alive, but all of that body's independent thought processes had ceased; only involuntary functions of the nervous system (such as those controlling the heartbeat) continued. Controlled by Ross's thought patterns, Zzzax tried unsuccessfully to kill both Bruce Banner and Rick Jones, who had recently become a Hulk-like monster himself. Zzzax's own consciousness resurfaced briefly, and fought for dominance of its physical form with the Ross persona, but the Ross consciousness again took control. The Ross persona had apparently become unbalanced by its absorption into Zzzax, and when Banner forced it to recognize that it inhabited a monster's form, the Ross persona was horrified. Still controlled by the Ross consciousness, Zzzax fled.  Eventually, Ross's mind returned to his original physical body, bringing much of Zzzax's living electricity with it. But now a new menace had come to Gamma Base: a grotesque mutant (The Nevermind), which seized upon the heads of humans victims and drained life-energy from their bodies, killing them. Ross watched as Rick Jones, in his Hulk-like form, tried unsuccessfully to defeat the mutant, which menaced Betty. Then, to save Betty, Bruce Banner hurled himself into the mutant's path, and thereby himself became the mutant's victim. On seeing the Hulk's bravery and Bruce Banner's self-sacrifice, Ross realized that he had gravely misjudged them both. The mutant rendered Bruce Banner unconscious without draining him of all his life energy, and then headed towards Betty. This time, Thaddeus Ross hurled himself into the mutant's path, and the creature took hold of his head. But since Ross still possessed much of Zzzax's electrical energy, the mutant could not take control of Ross's mind, and Ross released all of Zzzax's energy, electrocuting the mutant. Zzzax has since returned, however.