Odetta

Odetta (December 31, 1930 - December 2, 2008) was an African-American singer, actress, guitarist, songwriter, and a human rights activist, often referred to as "The Voice of the Civil Rights Movement." Her musical repertoire consists largely of American folk music, blues, jazz, and spirituals. An important figure in the American folk music revival of the 1950s and '60s, she was a formative influence on dozens of artists, including Bob Dylan, Joan Baez, and Janis Joplin.

http://en.wikipedia.org/wiki/Odetta