If anyone could claim to have "saved the world" it would be Vasili Arkhipov. He was a Soviet Navy officer who played a vital role in the Cuban Missile Crisis. His submarine was believed by its captain to be under attack from the U.S. Navy however the captain needed votes from all 3 senior staff members to fire a nuclear torpedo. Arkhipov was the only one sensible enough to vote no on the ship. If he had voted yes, then it was very likely that the Cold War would have turned nuclear and probably would have wiped humanity off of the earth.