Martin Luther King Jr. was the leader of the civil rights movement in the United States known for his nonviolent approach. He was a prominent advocate for racial equality and social justice during the 1950s and 1960s, inspired by principles of nonviolence and civil disobedience, influenced by Mahatma Gandhi. King's leadership in organizing peaceful protests, marches, and sit-ins galvanized public opinion against racial segregation and discrimination. His famous "I Have a Dream" speech, delivered during the 1963 March on Washington, highlighted his vision for a racially integrated and harmonious society. King’s efforts were pivotal in achieving landmark legislation like the Civil Rights Act of 1964.