6. Gerhard Domagk
Gerhard Domagk was a German scientist who is known for winning the Nobel Peace Prize for discovering the sulfa drugs, antibacterial sulfonamides, that would go on to be the basis for several well-known prescription medications. Later on in life, Domagk became obsessed with cancer research and hoped to find a way to kill cancer cells without harming normal ones.
Through his research, he sterilized human cancers and utilized tests on animals in order to develop a vaccine. When he was denied a human trial, Domagk proceeded to inject his serum into himself to see how the body would react. The move was highly controversial at the time and sadly did not yield the results he had hoped for.