The important figure in history who was a champion of social justice is Martin Luther King Jr.. A leader in the American civil rights movement, King is best known for his advocacy against racial discrimination and his commitment to nonviolent protest. His famous "I Have a Dream" speech captured the aspirations of millions for equality and justice in the United States. King’s efforts, including the organization of events like the March on Washington, were crucial in the fight for civil rights, leading to significant legislation such as the Civil Rights Act. His legacy continues to inspire movements for equality worldwide.