Some of the major civil rights leaders were Frederick Douglass, Martin Luther King, Jr and Malcolm X. Frederick Douglass was an early civil rights activist, while King and Malcom X were part of the larger Civil Rights Movement of the mid 1900s.
Frederick Douglass lived in the 1800s and was a slave from birth until he ran away at age 18, after learning to read and write at age 15. He put most of his efforts toward abolitionist work in hopes to end slavery. He toured the country speaking about his experiences as a slave and wrote numerous books. His freedom was bought by British supporters later in life. After the Civil War, he continued to fight for civil rights.
King lived from 1929 to 1968, when he was assassinated. He was a minister in Alabama and one of the key leaders in the Civil Rights Movement. During this time he preached peaceful protest and lead the famous March on Washington, where he gave his "I Have a Dream" speech.
Malcolm X was a more violent answer to King. He was part of the Nation of Islam, supported socialism and preferred a more direct approach to civil rights activism. Malcom X was assassinated in 1965.