https://allthatsinteresting.com/stanislav-petrov

Petrov did more for the human race than all Hollywood celebs combined, and I couldn't even remember his name, much less the date of his important decision.

Petrov was a few hours into his shift on September 26, 1983, as the duty officer at Serpukhov-15, the secret command center outside Moscow used for monitoring Soviet military satellites over the United States. Suddenly the alarms went off, warning that five Minuteman intercontinental ballistic missiles had been launched from an American base.

EDIT: ". . . deciding not to launch Soviet missiles" is a mis-characterization. Petrov decided not to report the alarm up the chain. He himself would not have been the one launching any missiles.

Petrov’s superiors were in charge of reporting any attacks to the general military staff, who would then report to Andropov, regarding a retaliation. He had to decide whether to report these missiles to his superiors and risk setting off an irreversible chain reaction.

Ultimately, he decided the reports were probably false, though he recalled later that there was only a 50-50 chance he was right. He claimed that he never trusted the early warning system.