Stanislav Petrov, a name everyone should be aware of. He quite literally saved humanity. Had he acted differently, large scale nuclear war would been initiated.
A Soviet nuclear strike warning system had malfunctioned. Stanislav Petrov was on duty and saw the system report the launch of five intercontinental ballistic missiles from the US headed towards them.
When it comes to nuclear strikes, you essentially have to make a decision to retaliate within a few minutes. There is almost no time for thorough deliberation.
Had Stanislav Petrov followed military protocol and reported the (nonexistent) incoming attacks, an all out retaliation would have been extremely likely.
He correctly recognized the possibility of a false alarm and saved humanity.