Winnie Madikizela-Mandela has died, according to her personal assistant.
The controversial South African activist headed the African National Congress Women's League, and held several government positions.
She was married to Nelson Mandela for 38 years, including 27 years during which he was imprisoned.
In a statement, her family said: "Mrs Madikizela-Mandela was one of the greatest icons of the struggle against Apartheid."
"She fought valiantly against the Apartheid state and sacrificed her life for the freedom of the country," reads the statement.
"Her activism and resistance to Apartheid landed her in jail on numerous occasions‚ eventually causing her banishment to the small town of Brandfort in the then Orange Free State.
"She kept the memory of her imprisoned husband Nelson Mandela alive during his years on Robben Island and helped give the Struggle for justice in South Africa one its most recognisable faces.
"She dedicated most of her adult life to the cause of the people and for this was known far and wide as the Mother Of The Nation."