Martin Luther King Jr. was a prominent leader in the American civil rights movement during the 1950s and 1960s. He advocated for nonviolent civil disobedience and delivered powerful speeches, including his iconic 'I Have a Dream' address. King's message of equality and justice continues to inspire people worldwide. His legacy is celebrated annually on Martin Luther King Jr. Day, which honors his contributions to the fight against racial inequality. King's leadership and vision played a crucial role in shaping the course of American history.