Linus Pauling
One of only two people to have been awarded a Nobel Prize in multiple fields (the other is Marie Curie), Linus Pauling was the ultimate poacher turned gamekeeper. In the first half of his career, Pauling blazed a trail as a world-leading chemist, working on several weapons projects for the U.S. military and winning a Nobel Prize for his groundbreaking research into chemical bonds. Then, struck by the grim realities of the nuclear era and the pacifist leanings of his wife Ava, Pauling became a fervent peace activist and later joined Albert Einstein and a number of leading scientists to call for the end of nuclear testing. His campaign was so vociferous that the U.S. State Department temporarily withdrew his passport and rumors of his alleged communist leanings began to swirl. As such, when he won the 1962 Peace Prize for his antinuclear campaign, his critics described him as a "naive spokesman for the Communist Party." Adding fuel to the fire a few years later, Pauling went on to receive the International Lenin Peace Prize from the U.S.S.R. in 1970.