During the fight against apartheid Mr Zuma was head of internal security for the ANC, when some people were killed and some tortured.
It is not clear how much he knew or sanctioned, says our correspondent.
But Mr Zuma is also a skilled conciliator, credited with ending the political violence in KwaZulu-Natal and helping to bring peace to Burundi.
Helen Zille, who received a hero's welcome in Cape Town, told the BBC the opposition had managed to reduce the ANC's grip on the country.
Celebrations in South Africa ahead of the ANC election victory
"The results are very good for South Africa," she told Focus on Africa.
"They are very good for democracy. The ANC is below the two-thirds majority they need to adversely change the constitution. The Democratic Alliance has grown by more than 30% nationally and we have doubled our vote in the Western Cape, where we've won the province which is wonderful."
Ms Zille said earlier the party would be looking to form a coalition.
Analysts say this is likely to be with Cope, formed by dissident ANC supporters of former President Thabo Mbeki who resigned last year after losing a power struggle with Mr Zuma.
African Union observer mission head Salim Ahmed Salim said the poll had been free, fair, transparent and credible.
Its vibrancy "had done honour not only to the people of South Africa but to Africa as a whole", he said.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.