- Socrates (c. 470-399 BC): The Greek philosopher Socrates refused to fight in the Peloponnesian War, citing his belief that war was immoral.
- Martin Luther King Jr. (1929-1968): The American civil rights leader and Christian minister Martin Luther King Jr. was a prominent conscientious objector during the Vietnam War, arguing that the war was unjust and immoral.
- Muhammad Ali (1942-2016): The American boxer and civil rights activist Muhammad Ali refused to be inducted into the United States Army during the Vietnam War, citing his religious beliefs as a Muslim.
- Dorothy Day (1897-1980): The American journalist, social activist, and Catholic convert Dorothy Day was a conscientious objector during World War I and World War II, citing her pacifist beliefs.
- Franz Jägerstätter (1907-1943): The Austrian Catholic farmer Franz Jägerstätter refused to fight for the Nazi regime in World War II and was executed for his refusal.
- Simone Weil (1909-1943): The French philosopher and mystic Simone Weil refused to accept a position as a nurse in World War II and was eventually deported and died of tuberculosis.
- Desiderio Costa (1889–1941): Italian Seventh-Day Adventist who spent 13 years of his life in fascist Italian prisons for his refusal to bear arms.
- James Nangle (1908–1988): New Zealander Methodist, who refused to serve in the military due to his pacifism and was jailed for it.