Stanislav Petrov is a rather famous person (of course only on Lesswrong, not in the real world).
But there is another Russian who saved the world: Vasili Alexandrovich Arkhipov.
On this day in 1962, at the height of the Cuban Missile Crisis Vasili Arkhipov prevented the launch of a nuclear torpedo and thus a possible nuclear war.
It's strange that Petrov attracts much more attention than Arkhipov. E.g. googling "Stanislav Petrov" produces 101.000 results, "Vasili Arkhipov" only 9.040 results. By contrast searching for "Britney Spears" generates about 295.000.000 results. Sorta depressing.
Anyway, let this day be the Vasili Arkhipov Day.
There might be a few unknown Vasilis/Stanislavs, and a couple of actions/inactions of leaders (e.g., Kennedy) that prevented a world-wide disaster, but before the atomic age it would be hard to single-handedly cause a civilization-threatening disaster.
This has not stopped writers and movie-makers to explore the trope ad nauseam though...
Favouring nomination of Kennedy.
Curtis LeMay was Chief of Strategic Air Command:
During the Cuban Missile Crisis in 1962, LeMay clashed again with U.S. President John F. Kennedy and Defense Secretary McNamara, arguing that he should be allowed to bomb nuclear missile sites in Cuba.
He opposed the naval blockade and, after the end of the crisis, suggested that Cuba be invaded anyway, even after the Russians agre... (read more)