Madikizela-Mandela was married to Nelson Mandela from 1958 to 1996.
Mandela was imprisoned throughout most of their marriage and Madikizela-Mandela's own activism against the apartheid regime led to her being imprisoned for months and spending years under house arrest.
Her political activism was marred by a kidnapping and assault conviction in 1991, for which she was fined.
She faced these allegations again during the 1997 hearings before the Truth and Reconciliation Commission, a panel that investigated apartheid-era crimes.
As a parliamentarian after South Africa's first all-race elections, she was convicted of fraud.
Still, she was widely venerated in South Africa for her role in fighting white minority rule.