Tributes are pouring in for the Mother of the Nation, Mama Winnie Madikizela-Mandela, who died on Monday at the age of 81, after a long illness.
Politicians were among the first to send their condolences.
United Democratic Movement leader Bantu Holomisa said he was shocked at the news.
"I recently saw Winnie talking and joking about politics in the country. I pass my condolences to her friends, family and the ANC.
"I think there is sufficient consensus that she is a brave person who contributed immensely to the freedom of this country."
Holomisa said he had worked closely with Madikizela-Mandela in the 1980s.
"I remember Winnie called for the reburial of King Sabata Dalindyebo, and we facilitated that. That was in 1989. When Madiba was released in 1999, she said that he could not be guarded by De Klerk's security. We had to wait for MK to return to SA, so we sent the Transkei defence force to guard him.
"She had a good sense of humour, but sometimes her boldness would annoy Madiba. Sometimes he would say: 'Bantu control your mother. She is ungovernable'. That would be when she attacked his governance."
Congress of the People leader Mosiuoa Lekota said: "I received with shock and great sadness the news of Winnie Madikizela's passing. She is an outstanding symbol and champion of racial and gender issues.
"She is an inspiration to all South Africans - to stand up and emulate the strength and audacity with which she fought for the rights of people in this country. May God let her rest in peace."
'A liberation stalwart of epic stature'
The Democratic Alliance's Mmusi Maimane said: "It is a deeply sad occasion for the people of South Africa. This was someone who has run an incredible race. It is not only us as South Africans, but the continent as well as the global village, that have experienced a loss."
Maimane extended his condolences to the family.
Other politicians took to social media platforms to express their sadness over Madikizela-Mandela's death.
The IFP's Mkhuleko Hlengwa tweeted: "A sad loss indeed... May #WinnieMandela now rest in God's perfect peace. She ran her race and was a liberation stalwart of epic stature. Her sacrifices, bravery and persecution contributed significantly to the securing of our freedom and democracy!"
Cooperative Governance Minister Zweli Mkhize tweeted: "#WinnieMandela "Struggle Icon, freedom fighter, Mother of our nation ... May her soul rest in eternal peace."
Zelda la Grange, the former private secretary to Nelson Mandela, also sent her sincere condolences.
"They say life can never be the same after the death of one's mother, irrespective of your relationship with her."
La Grange said South Africans had lost a mother today.
'Her courageous defiance was deeply inspirational'
"May they find solace in the fact that their mother's place in history is inscribed with the great. Her sacrifices, the courage of her conviction and for keeping the hopes and spirit of Nelson Mandela and others alive during the struggle will always be remembered and appreciated.
"While we mourn with her children, we thank her family for sharing her strength and courage with the world. May she rest in Peace. Hamba Kahle Aunt Winnie!"
Minister in the Presidency Nkosazana Dlamini-Zuma tweeted: "Just received the shattering news of the passing mama Nomzamo ... Hamba Kahle Mbokodo."
Archbishop Emeritus Tutu said: "May Mam' uWinnie rest in peace and rise in glory."
He said Madikizela-Mandela was for many years a defining symbol of the struggle against apartheid.
"She refused to be bowed by the imprisonment of her husband, the perpetual harassment of her family by security forces, detentions, bannings and banishment. Her courageous defiance was deeply inspirational to me, and to generations of activists.
"Leah and I send our heartfelt condolences to her daughters, grandchildren and extended family. May she rest in peace and rise in glory."
'Mother of the Nation'
Family spokesperson Victor Dlamini announced earlier that Madikizela-Mandela had died at the Netcare Milpark Hospital, Johannesburg.
"She died after a long illness, for which she had been in and out of hospital since the start of the year. She succumbed peacefully in the early hours of Monday afternoon, surrounded by her family and loved ones."
Dlamini said 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. 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."
The family said she had dedicated her adult life to the cause of the people, and "for this was known far and wide as the Mother Of The Nation".
Dlamini said the Mandela family was deeply grateful for the gift of her life.
"Even as our hearts break at her passing, we urge all those who loved her to celebrate this most remarkable woman."
Dlamini said the family would release details of the memorial service once they had been finalised.