Sheena Duncan (7 December 1932 – 4 May 2010) was a South African anti-Apartheid activist and counselor. Duncan was the leader of Black Sash, a group of white, middle-class South African women who offered support to black South Africans and advocated the non-violent abolishment of the Apartheid system. For her activism, Duncan was the 1986 recipient of the Prize For Freedom. She was also awarded the Order of Simon of Cyrene, by the South African Council of Churches and made Grand Counsellor of the Order of the Baobab (in Silver). She received honorary doctrates from the University of Cape Town, the University of the Witwatersrand and the University of KwaZulu-Natal.
Duncan wrote several articles, booklets and pamphlets, especially on issues such as forced removals and pass laws. In the 1970s, she joined the Anglican Church's Challenge Group, a movement that sought to end racism within the church. She also represented the Anglican Church on the South African Council of Churches' (SACC) Justice and Reconciliation Division.
Duncan died at her home in Johannesburg, South Africa, of cancer on 4 May 2010, at the age of 77. She leaves two daughters, Lindsay McTeague and Carey Haouach and two grand children.