Astronaut
The first civilian in space was Valentina Tereshkova aboard Vostok 6 (she also became the first woman in space on that mission).
Tereshkova was only honorarily inducted into the USSR's Air Force, which did not accept female pilots at that time. A month later, Joseph Albert Walker became the first American civilian in space when his X-15 Flight 90 crossed the line, qualifying him by the international definition of spaceflight. Walker had joined the US Army Air Force but was not a member during his flight. 
The first people in space who had never been a member of any country's armed forces were both Konstantin Feoktistov and Boris Yegorov aboard Voskhod 1.
Kathryn D. Sullivan
In 2014, Sullivan was honored in the Time 100 list. According to John Glenn, "Kathy is not just an ivory-tower scientist. She was part of NASA's first class of female astronauts, selected in 1978, and went on to fly three shuttle missions. She is the first American woman to walk in space and served aboard the mission that deployed the Hubble Space Telescope. That role in helping humanity look outward has not prevented her from looking homeward. The planet is suffering increasingly severe upheavals, at least partly a result of climate change — droughts, floods, typhoons, tornadoes. I believe my good friend Kathy is the right person for the right job at the right time."