Earth Z-Omega-1(extinct) is the designation of a cataloged but unexplored close-offshoot reality to Earth Prime. First contact was made on October 2, 2008, when Dr. Alexander Atom of Earth Z-Omega-1(extinct) made contact with his Earth Prime counterpart by means of an experimental interdimensional communications array. During the course of the contact, Dr. Atom (Prime) was able to elicit information about the alternate universe from his counterpart, as well as arrange for the refugee transfer of one survivor from the series of disasters that rendered the world uninhabitable.

The designation, which uses Freedom League Standard Notation, indicates the planet's status:

• Earth: This universe is a parallel Earth world and English is or was a dominant language.
• Z: This universe is hostile, unexplored, and uninhabitable. No further in-person research is planned.
• Omega: This universe is suspected to have fallen under the influence of the Terminus.
• 1: This is the first universe of its kind discovered.
• Extinct: This parallel Earth once harbored a Primelike population, but the entire population has since been wiped out.

It is difficult to pin down the first point of divergence between EZO1 and Prime, but the most likely point for major divergence occurred in the fall of 2006. What on Earth Prime was a largely overestimated outbreak of avian flu strain H5N1 through the fall and winter of 2006, on EZ01 mutated into a previously unseen and far more deadly strain of virulent influenza, dubbed “the hero flu.” The new strain was transmittable through most known vectors, and carried an extraordinarily high morbidity and mortality rate. Like H5N1, it began in Southeast Asia, but spread quickly through the entire world, often with no identifiable point of contagion. Investigation into the outbreak pattern of the disease was hampered greatly by the speed at which carriers succumbed and the rapid degradation of conditions in major universities and laboratories around the world. Researchers estimated that up to one in three human beings would die of the new strain of flu by the end of 2007 if the virus could not be contained. Unlike many strains of influenza, the young and healthy showed no more resistance to the hero flu than the infirm. Reports indicated that in fact metahumans with clearly superior immune systems were still vulnerable, and often succumbed even faster than unaugmented humans to the disease, hence the colloquial name.

By March of 2007, according to survivor testimony, martial law was declared in major U.S. cities and government infrastructure began shutting down. In desperation, the CDC and WHO, in close cooperation with the Freedom League and UNISON released an experimental vaccine. No vaccine had been created that could stop the virus, instead, the vaccine was designed to augment the bodies of victims so that they could withstand the ravages of the flu long enough for its relatively brief latency to pass. In initial tests, the vaccine appeared successful, with victims recovering in controlled conditions. The vaccine entered mass emergency production worldwide, in an unprecedented effort at 100% worldwide vaccination, assisted by nearly every surviving superintellect of every affiliation. Simultaneous vaccine programs began around the world on 18 April, 2008, reaching over seven hundred fifty million people in the fourteen days following its deployment, in an effort that spanned all continents and known people groups.

Initial responses to the vaccine were highly favorable, with an immediate and dramatic lowering of the death toll from the hero flu. In fact, there were no reported casualties from flu among the vaccinated population, even among those who had already been gravely ill. Some rioting was reported outside vaccination centers as families camped in lines for days to wait for doses to become available. After the fifth day of the vaccination program, irregularities were reported among the vaccinated population, brain dead patients who still exhibited substantial motor function, patients whose bodies combated the flu symptoms at the expense of higher mental functions, even several reported cases of vaccinated persons who did not contract the flu activating the vaccine's response through other, lesser calls on the immune system. Affected persons were quarantined, but the immunization program continued for another seven to nine days.

On 1 May, 2007, the WHO called for an immediate halt to all vaccination programs, and for the destruction of any remaining stores of vaccine. Continued observation of vaccinated persons had proved conclusively that the vaccine was extraordinarily destructive to higher brain function, in essence preserving the body by destroying the mind. Victims of the vaccine's ill effects became zombielike, extremely strong and resilient, able to survive conditions that would normally cause death, but with no observable higher functions. They existed, in essence, merely for the sake of continued existence. They were also observed to be extremely hostile to human life, reacting with violence when faced with unaffected human beings. Despite these reports, the continued spread of the hero flu led many people to seek the vaccine anyway. Eyewitness reports of the time indicate that few vaccines were destroyed, and that most were sold on the black market before the full effects of the drugs became known.

Quarantine areas for the so-called “zombies” were quickly erected, but seem to have had little effect. The vaccination program had focused heavily on health care workers, public servants, and the armed forces in many countries, leaving those individuals who were the most necessary for successful quarantine the most likely to require it themselves. Quarantine procedures rapidly broke down, and violence became widespread throughout major cities as the vaccine's victims spread out and began killing those who had not been affected. With the decline of military and police power, governmental infrastructure around the world began to collapse, along with transportation and communication. On 13 May, 2007, the Office of the President of the United States released a final press release asking for citizens to remain calm and stay in their homes if at all possible, and promising that a new vaccine would be forthcoming soon.

After this point, it becomes impossible to frame a coherent timeline of world events, due to the breakdown in global communications and a lack of survivor knowledge. The lone human refugee to arrive on Earth Prime was debriefed, but due to isolation and tender years could not place dates on any events after May of 2007, but states she did not encounter any survivors after that month until the early summer of 2008, when she found a single pocket of perhaps two dozen survivors. Projections conducted by Dr. Atom EZO1 suggest the survival of perhaps as little as five thousand human survivors worldwide, probably in pockets of no more than thirty or forty individuals. The disposition of this world's nonhuman and potentially immune superheroes and supervillains could not be ascertained, but Dr. Atom theorizes that many of them left when it became obvious that there was nothing left to save.

This universe is currently under strict quarantine by the Freedom League, and is not slated for any further investigation or development. All information regarding this world's existence and its history are classified. The one refugee survivor, an adolescent metahuman, was thoroughly decontaminated and debriefed, and has been assisted into a new life on Earth Prime. No sample of the pathogen which caused the hero flu was discovered on the refugee or in the air sample that arrived with her, but the continued presence of the flu in that timeline has not been ruled out. Experimentation to discover the nature of the pathogen and possible treatment has been vetoed as excessively risky, given the conditions on the world and the known deadliness of the viral strain. Dissemination of information regarding this timeline is unlikely to contribute to scientific discourse, and has been deemed very likely to contribute to public unease on Earth Prime, and so shall remain classified indefinitely.

Dr. Atom EZO1 ceased communication with Earth Prime on 3 December, 2008, after conveying what information he had and ascertaining that the refugee he delivered was healthy and being cared for. His last message was an expression of remorse for his work on the vaccine project, along with a quote from John Donne. Before the cessation of contact, Atom provided his theory as to the divergence. He theorized that the hero flu was not a naturally occurring pathogenic strain, but had been introduced by an outside force looking to diminish or destroy humanity. In a communication on 28 November, 2008, Atom indicated that ships of unknown configuration were approaching Earth, but remained outside satellite communication range. Dr. Atom Prime and the Earth Prime Freedom League suspected at the time that the events on EZO1 may be directly related to the activities of Omega and the Terminus.

In the spring of 2011, the members of Claremont Academy's superteam Young Freedom returned from an interdimensional mission that included a stay on EZO1(e). They reported that the world had been overrun by Omegadrones in the intervening three years and had become an outpost for Physician Friendly, who admitted to engineering the hero flu. The heroes reported that they destroyed the majority of the Terminus presence on the world, in part by sealing its Freedom City into the Zero Zone with the help of veteran hero Rick Lucas. It is unknown whether further travel to EZO1(e) would be possible now by any means, but as the world remains under strict interdiction, no investigation is planned.

In 2010, the Young Freedom superteam, again on an interdimensional mission, encountered a dimensional doppelganger of the superheroine Wander on Earth V-Malign-1(enemy), commonly known as Anti-Earth. This doppelganger, codenamed Singularity, was found to be from a closed-loop dimensional offshoot of EZO1(e) that probably existed for only a few hours. This offshoot timeline was designated Earth-Z-Omega-2(extinct).