a black US religious leader who became the most important leader of the civil rights movement and worked hard to achieve social changes for black people. He was a great public speaker, and many people remember his famous speech that starts with the words "I have a dream". He encouraged people to try to achieve changes without using violence, and in 1964 he won the Nobel Peace Prize. In 1968 he was shot and killed in Memphis, Tennessee. In the US there is a national holiday in January to celebrate his birthday (1929-68)