IN THE BEGINNING...
For Whom the Watchers Watch. The ancient race known as the Watchers are unique among the multiverse. They exist in parallel in every universe of the multiverse and are sworn to observe the evolution of each with a strict vow of non-interference. But why? Why must the Watchers watch? The first species to evolve the ability to manipulate cosmic energy, the Watchers were scientists of the highest order, their appetite to know all that was knowable was not satiated by cataloging every corner of the early universe.
The Watchers wanted to know what lay beyond the veil of the boundaries of space itself. It was for this purpose that they create the first interdimensional portal to observe the multiverse. A species so advanced so early in the development of a universe drew the attention of arbiter of the multiverse, the Living Tribunal. The Watchers were the most powerful beings in the young universe and their curiosity made them a potential danger to the multiverse. The standard judgment of the Tribunal would be to destroy the universe and remake it minus the threat, but the Tribunal saw a use for their unique abilities.
The Watchers swore allegiance to the Tribunal (who they saw as a god-like being) and were commanded by him to observer every corner of the expanding universe. They were given knowledge of all possible futures and each was equipped with a portal that allowed them to share knowledge with their counterparts in every universe in the multiverse. They would act as the eyes of the Tribunal, recording any anomalies that might threaten the multiverse.
A mere million years after the Watchers charge, their first great event would be the birth of the first Celestial. The first Celestial started out as the evolved consciousness of billions of individuals in a single galaxy. Their combined psionic might was able to form all the matter and energy of their galaxy into a singular form and thus was born The One from All. This first Celestials singular focus was the creation of others of his kind by cultivating sentience in every galaxy in the universe. Now, there are hosts of Celestials in every galaxy experimenting with fledgling races, coaxing them to reach their potential.
Once a galaxy is saturated with sentient life capable of evolution beyond physical form, the tending Celestials collapse the galaxy around the singularity at its center, using that mass and energy to birth a new Celestial. The Watchers observed the Celestials carefully and determined that their rise would lead to an early collapse of the very universe itself, a Big Crunch. An alternate possibility would present itself in the form of…
The sole survivor of the death of the universe that existed before this one, the being known as Galactus incubated for several million years after the Big Bang. His emergence would signal the end of the proliferation of Celestials throughout the universe. Galactus’s cosmic power is fueled by a hunger for the energies of planets capable of supporting life, but not just any life, the sentient life cultivated by Celestials.
In every galaxy where there are hosts of the Celestials, there would be an aspect of Galactus, reaping the worlds they have sown. As Galactus’s hunger grows, it became harder and harder for new Celestials to come into being, reducing their numbers and making Galactus their mortal enemy. To the Watchers, Galactus posed an opposite, yet equal threat that could lead to a premature Heat Death of the universe. Maddened by the bleak and conflicting visions of the future, the Watcher Ecce, who witnessed the birth of Galactus and had even considered breaking his vow to destroy the entity while in its nascent state, decided to instead deny both Galactus and the Celestials their prize by creating a device capable of sterilizing whole galaxies of life. The device, dubbed the Ultimate Nullifier, wielded by the mad Watcher Ecce, caused untold destruction across millions of parsecs of space before he was finally defeated by the combined might of his fellow Watchers.
Realizing the potential temptation a device like the Nullifier posed, it was decided that it would be entrusted to the one being in the universe with the power to protect it, but never use it, Galactus.