Rachel Carson author of Silent Spring who warned of chemicals in the environment which led to the formation in the US of the EPA (Environmental Protection Association) https://study.com/academy/lesson/video/silent-spring-by-rachel-carson-summary-analysis.html

Daniel Ellsberg who leaked the Pentagon Papers that told the public the truth about the Vietnam war, and who spent his entire life educating the public about the dangers of the MIC. http://scua.library.umass.edu/ellsberg-daniel/

Just a few.