The notable leader assassinated in 1963 while advocating for civil rights was Dr. Martin Luther King Jr. His assassination on April 4, 1968, shocked the nation and the world, marking a significant moment in the American civil rights movement. King was a prominent advocate for nonviolent protest and played a pivotal role in advancing racial equality through campaigns against segregation and injustice. His work inspired generations and galvanized support for civil rights legislation. King's legacy endures as a symbol of the ongoing struggle for justice and equality in America, making his assassination a major turning point in the movement.