Ever since his debut in FANTASTIC FOUR (1961) #13, Uatu the Watcher has observed everything that has happened in the Marvel Universe. Even the Multiverse stories of WHAT IF? (1977) fall under the Watcher’s relentless gaze. Like the rest of his cosmic race, the Watcher is forbidden from directly interfering in the events of other species. But Uatu has had difficulty keeping that oath...
The event that forced the Watchers to take a non-interference vow. Uatu’s father convinced the Watchers that they had an obligation to help younger species of the universe. Uatu’s people embraced that ideal, and helped Prosilicus by introducing technology that was several thousands of years ahead of their time. However, Prosilicus was destroyed by its people when they used that technology to make war on each other.
When Galactus came to Earth, Uatu went out of his way to ensure humanity’s survival. First, Uatu tried to hide Earth from the Silver Surfer behind an illusion of atmospheric disasters. He also took the unusual step of directly warning the Fantastic Four that they had to prevent Silver Surfer from summoning his master, Galactus.
You may have noticed that the Watcher helps out the FF a lot. That fact didn’t escape the attention of Uatu’s fellow Watchers. That’s why they placed their brother on trial. In the end, Uatu was contrite about his shortcomings and he vowed that his days of interfering in Earth’s affairs would come to an end. But it was an oath that Uatu would break again and again...
Following Galactus’ incursion and defeat in FANTASTIC FOUR (1961) #243-244, Mister Fantastic went above and beyond by saving Galactus’ life. When the other alien races discovered Reed Richards’ actions, they placed him on trial for his life. Rather than let Reed twist in the wind, Uatu acted as his lawyer, convincing the assembled that the course of action was justified because Galactus serves a greater purpose.
Not every Watcher shares Uatu’s benevolence. When the Celestials threatened to destroy their race, Uatu’s nephew Aron sought to survive at all costs. After the FF were able to stop the Celestials, Uatu took matters into his own hands and fought Aron, transforming him into living energy. The other Watchers swiftly exiled Uatu and stripped him of his position, yet he was only absent from his duties for a short time...
In the wake of Uatu’s death in ORIGINAL SIN, Nick Fury was punished by the Watcher’s people and forced to become “the Unseen,” acting as the Watcher’s replacement on Earth. But in the aftermath of EMPYRE, the Unseen realized that there was another player behind the Cotati’s warlike aggression. He also recognized the Cotati’s weapons. At that moment, Uatu resurrected himself and got caught up on what he had missed.