The man who saved the world:
Stanislav Petrov was manning surveillance equipment for the Soviet Air Defense Forces when he noticed something strange on the screen. Soon after, warning signals started flashing with the report of an incoming nuclear missile from the USA.
Seeing only one missile, he figured it was a mistake, assuming Americans wouldn’t send only one missile if they wanted a nuclear war.
Soon thereafter, many more started appearing on the screen.
Nevertheless he trusted his instincts, and rather than contact his superiors he waited to see what would happen. He waited past the perceived time on impact. There was no damage - the warnings were due to a system malfunction.
Had Petrov not defied protocol and contacted his superiors, a real retaliatory strike may very well have been fired in response - igniting nuclear war between the USA and Soviet Union.