Remembered for his work with jazz musician Duke Ellington, as well as for such solo hits as "He" and "Danny Boy," this pop and R&B singer was also a prominent civil rights activist of the 1960s.

Remembered for his work with jazz musician Duke Ellington, as well as for such solo hits as "He" and "Danny Boy," this pop and R&B singer was also a prominent civil rights activist of the 1960s.