The first man to enter space and return safely was the Russian
Yuri Alekseyevich Gagarin who travelled into space on 12th April
1961 after being launched on Vostok 1. Sadly, he was killed in a
routine plane crash on 27th March 1968.
There have been many conspiracy theories surrounding Gagarin's space flight as no one in the Western world knew about it until its completion and Gagarin had returned safely. This led many conspiracists in the West (especially in the USA, who were pipped at the post to get the first man in space) to suggest that Russia had already sent many men up into space, but they had perished there, and Russia kept quiet about these events. However, these stories were simply propaganda by the USA as there was abcolutely no evidence of anything untoward in the Russian spece programme.
Gagarin's body is now buried in Red Square, Moscow.