The leader of the American Civil Rights Movement known for advocating nonviolent protest was Martin Luther King Jr. He championed the principles of civil disobedience and nonviolence, inspired by Mahatma Gandhi’s philosophy. King played a pivotal role in significant events like the Montgomery Bus Boycott and the March on Washington, where he delivered his iconic "I Have a Dream" speech. His leadership and rhetoric galvanized public support for civil rights legislation, resulting in landmark laws like the Civil Rights Act of 1964 and the Voting Rights Act of 1965. King's legacy continues to resonate in ongoing struggles for social justice.