On 12 April 1961, Yuri Gagarin, a young, smiling fighter pilot personally selected by Soviet Chief Designer Sergei Korolev, crammed himself into a metal sphere and was hurled into orbit by Korolev's R-7, a variant of the world's first ICBM. Gagarin completed just short of a single orbit (the Soviets maintained for decades it was a complete orbit) and became world-famous. He wasn't allowed to fly again for several years, as the government feared the public relations nightmare of losing him. (He also apparently annoyed some people with his critiques of the later Soyuz 1 flight, in which cosmonaut Vladimir Komarov was killed.) He did extensive engineering work on long-duration space flights and reusable space vehicles, a subject near and dear to my heart.
He finally argued his way back to flight status and was training when his jet crashed in 1968.
Gagarin himself was a great public face for his country but not one of the more poetic astronauts/cosmonauts: there are few memorable quotes from the first man in space. He was a highly motivated pilot and cosmonaut, diligent in training, excellent in the mathematics of space flight. He was also, importantly, 5 feet 2 inches tall. Soviet officials tended to indicate he's noted there was no God visible in space, but Gagarin apparently never said anything on the subject and at home observed some Christian traditions.
So farewell, Yuri, wherever you are.
For the events leading up to human spaceflight, read (of course)
The First Space Race: Launching the World's First Satellites
(Matt Bille and Erika Lishock, 2004)
"This represents the best narrative available synthesizing this story. The authors also make some key contributions that have not been explored before." -- Dr. Roger D. Launius, National Air and Space Museum