Martin Luther King Jr. is renowned for his powerful speeches that significantly shaped America's identity in the 20th century. His oratory, infused with passion and conviction, galvanized the Civil Rights Movement. Notable speeches like "I Have a Dream" and "I've Been to the Mountaintop" articulated a vision of equality and justice, striving for a society where people are judged by their character rather than skin color, leaving a lasting impact on the pursuit of civil rights.