At some point in Overwatch’s past, all the world's omniums turned rogue and began building robots powered by evil AIs. Many of these robots were Bastion attack units, leading to crisis throughout the world (except for Russia). To date, no one knows the exact cause of the Omnic Crisis.

To respond to the threat, the United Nations formed Overwatch. This international task force gathered the best the world has to offer in military force and technology. In time, Overwatch disposed of the omnic threat and became a group of celebrated heroes across the world.

In the early years of the Omnic Crisis, Overwatch's two most powerful soldiers were Gabriel Reyes and Jack Morrison. Eventually a rift developed between the two. While Reyes was initially in command of the unit, Morrison eventually became their strike commander, effectively making him Overwatch's lead officer and most well known member. Reyes took to Blackwatch, a covert ops division of Overwatch. Morrison's second-in-command and one of the founding members of Overwatch was Ana Amari. She is considered one of the world's deadliest snipers.

From Europe came three of Overwatch’s most notable heroes. Torbjörn Lindholm was Overwatch’s master armorer, responsible for keeping his fellow agents protected. He also created the legendary armor for Reinhardt Wilhelm, the hulking, hammer wielding knight. And finally there was Angela Ziegler, aka Mercy. She served as Overwatch’s head of medical research.

Russia was able to handle the crisis on its own, without the aid of Overwatch. Its armies alone were able to hold off the waves of omnics.

After Overwatch and other nations banded together, the Omnic Crisis came to an end. Most of the world's omniums were shut down and every Bastion unit was destroyed… except for one.