Uatu is one of the Watchers who had observed the Multiverse from his place in the Nexus of All Realities becoming known as The Watcher. Along with his fellow Watchers, Uatu abides by an oath that prohibits him from interfering with events occurring within the realities he observes. This changed when an Infinity Stones-wielding Ultron sensed his presence and learned of the Multiverse, thus forcing him to violate this oath in order to protect the numerous timelines threatened by the omnicidal A.I.. Recruiting Captain Carter, Star-Lord, Doctor Strange, Erik Killmonger, Gamora, Thor and later Black Widow as the Guardians of the Multiverse, they were successful in preventing Ultron from advancing his devastation to much of the Multiverse.