The key figure in the civil rights movement who was assassinated in 1968 was Martin Luther King Jr. His advocacy for nonviolent protest and civil disobedience played a crucial role in addressing racial injustice and discrimination in the United States. King was a prominent leader during the Montgomery Bus Boycott and the March on Washington, where he delivered his famous "I Have a Dream" speech. His assassination on April 4, 1968, in Memphis, Tennessee, sent shockwaves through the nation and ignited riots in many cities, but his legacy continues to inspire movements for equity and justice.