Everyone knows Yuri Gagarin was the first human in space, right? Right? Well, it pays to remember that Soviet Russia was very big into shouting its triumphs and hidings its mistakes, and there are a lot of people out there who think that there may have been a lot more cosmonauts than the Kremlin admits, ones who died during the process. They believe two more missions were launched prior to Gagarin's, and that the pilots didn't survive the process. It was only because Yuri's was successful that they released the information. This would be in keeping with the USSR's propaganda views, but there's not much evidence supporting it.