Milt Campbell, an outstanding all-around athlete who was the first African-American to become an Olympic decathlon champion, died on Friday at his home in Gainesville, Ga. He was 78.

The cause was prostate cancer, said his companion, Linda Rusch.

Campbell, who won the decathlon at the 1956 Summer Olympics and had also played football professionally, sometimes expressed frustration that he was less well known than the four other Americans who became Olympic decathlon champions from 1948 to 1976: Bob Mathias (twice), Rafer Johnson, Bill Toomey and Bruce Jenner.

Each of those four was acclaimed the world’s greatest athlete and received endorsement contracts and acting roles. Mathias became a five-term congressman, Johnson a confidant of the Kennedy family. Campbell, in contrast, remained relatively unknown.

“I’ve probably been the greatest athlete this country has ever seen,” he said, immodestly but perhaps not inaccurately, in a 1980 interview with The New York Times. And yet, he added, he had not been invited to appear at a recent televised tennis tournament that featured Toomey, Johnson and others billed as “America’s greatest athletes.”