Chester Williams, the left winger in South Africa's side that won the 1995 Rugby World Cup, died on Friday aged 49, a relative told AFP.
It is believed Williams suffered a heart attack in Cape Town, where he lived and worked as a rugby coach at the University of the Western Cape.
Williams was the only black player in the World Cup-winning side that defeated rivals New Zealand 15-12 after extra time at Ellis Park stadium.
The Springboks team was reserved for whites in the apartheid era until 1981 when the first black player, fly-half Errol Tobias, was selected.
Williams died less than two months after the death of James Small, the other winger in the 1995 side.
He made his Springboks debut in 1993 against Argentina and scored 14 tries in 27 Test appearances over seven years.
"The news of Chester's passing is devastating and hard to believe, as he was still young and seemingly in good health," said SA Rugby president Mark Alexander.
"Chester was a true pioneer in South African rugby and his performances at the World Cup in 1995 will forever be etched in the hearts and minds of our rugby public.
"He was not only well known in the rugby fraternity, but was a much-loved South African whose influence stretched wider than just the rugby world.
"He was passionate about rugby and South Africa and as coach, at various levels, selflessly gave back to the game after he hung up his boots.
"Chester played with courage and was a beacon of light in his community and in the broader South African context.
"Chester Williams had so much more to give. Our thoughts and condolences are with his wife Maria, his children, family and friends during this very sad time."