Vladimir Komarov was selected as the Captain of the USSR Soyuz 1 mission. When he and his friend Yuri Gagarin inspected the spacecraft, they found 203 problems. Yes, you read that number right. Amazingly, Komarov still agreed to go on the mission.
Komarov reported the problems in hopes of getting the craft fixed, but anyone who saw the letter he wrote were diplomatically isolated or demoted, and the note never made it's way far enough up the chain of command.
Despite knowing full well that he would die on the mission, Komarov did not refuse going. He said goodbye to a good friend of his who then asked the obvious question, "Why not just refuse to go?"
Komarov, "If I don't make this flight, they'll send the backup pilot instead."
Who was the backup pilot? Kamarov's close friend and Russian hero, Yuri Gagarin. Sure enough, Kamarov died on reentry, all to save his friend from death. That's pretty much the definition of a hero.
