There are two American singers, father and son, named 'Robert McFerrin'. This article discusses Robert McFerrin, Sr. For Robert McFerrin, Jr., see Bobby McFerrin.
Robert Keith McFerrin Sr. (March 19, 1921 – November 24, 2006) was an American baritone. He was the first African American to be given a contract with the Metropolitan Opera and the first African American male to sing on the stage of The Met. (Marian Anderson was the first African American to actually sing on the Met's stage, but McFerrin had been awarded a contract first.)
McFerrin was also the first African American to sing at a title role at the Met, and the first to sing at both the Metropolitan Opera and the New York City Opera. Later, he sang the lead for the 1959 film Porgy and Bess (film), dubbed for Sydney Poitier.
Despite his voice and musical accomplishments, McFerrin did not achieve the lasting fame of other opera singers. This is most likely due to racism, as he was born in a time when the world of opera was still segregated. Not being 'allowed' to singing leading roles onstage was one of the reasons he left the Met for Hollywood:
"I had been [at the Met] for three years and had done only three roles, which averaged out to a role a year," he told music scholar Naymond Thomas in the mid-1980s.
"I did not want to continue the uncertainty of my future of whether or not I would progress beyond the status of singing the role of a brother or father," he added. "I wanted to sing Wotan or Count di Luna or a romantic lead. I guess this would have created too much controversy. Therefore, I simply chose to resign my position on the Met roster and take my chances in Hollywood." 
McFerrin later contracted Alzheimer's disease. He died in St. Louis in 2006 following a heart attack 
Robert McFerrin was the father of Grammy-award winning singer Bobby McFerrin.
- From his obituary in the Washington Post: http://www.washingtonpost.com/wp-dyn/content/article/2006/11/28/AR2006112801534.html Retrieved 8 January 2011
- Washington Post Obituary, op.cit.