Oliver Reginald Kaizana Tambo (27 October 1917 – 24 April 1993) was a South African anti-apartheid politician, activist, and revolutionary who served as President of the African National Congress (ANC) from 1967 to 1991.

Oliver Tambo was born on 27 October 1917 in the village of Nkantolo about 20 kilometres from Bizana; eastern Pondoland in what is now the Eastern Cape. Pondoland , known for its rich, fertile land, was the last chiefdom in South Africa to remain independent; its annexation by the British in the late 19th century marked the final stage of colonial dispossession in the region .Most of the people in the village were farmers.

His father, Mzimeni Tambo, was the son of a farmer and an assistant salesperson at a local trading store. Mzimeni had four wives and ten children, all of whom were literate. Oliver's mother, Julia, was Mzimeni's third wife. Tambo's father was very aware of the British annexation, and expressed sentiment by naming Oliver,"Kaizana", after the German Kaiser Wilhelm II, Britains enemy during World War I.

Oliver began his formal education at the age of seven at the Ludeke Methodist School, and completed his primary education at Holy Cross Mission. He later moved to Johannesburg where he attended St Peter’s College (present day St. Martin's School) in Rosettenville graduating in 1938 as one of the top students. Tambo initially wanted to study medicine but at the time, black students were not allowed to. he then opted to study sciences when he was admitted to the University of Fort Hare but in 1940 he, along with several others including Nelson Mandela, was expelled for participating in a student strike led by him in demand of a democratically elected students council. In 1942, Tambo returned to his former high school in Johannesburg to teach science and mathematics.Where he taught some future prominent figures like Duma Nokwe, first African Supreme Court advocate and later on went on to became the secretary-general of the ANC.

In 1944, along with Nelson Mandela, and Walter Sisulu, Tambo founded the ANC Youth League, with Tambo becoming its first National Secretary and a member of the National Executive in 1948. The Youth League proposed a change in the tactics of the anti-apartheid movement. Previously, the ANC had sought to further its cause by actions such as petitions and demonstrations; the Youth League felt these actions were insufficient to achieve the group's goals and proposed their own "Program of Action". This program advocated tactics such as boycotts, civil disobedience, strikes, and non-collaboration.

In 1955, Tambo became Secretary-general of the ANC after Sisulu was banned by the South African government under the Suppression of Communism Act. In 1958, he became Deputy President of the ANC and in 1959 was served with a five-year banning order by the government.

After the Sharpeville massacre on 21 March 1960 Tambo was sent abroad by the ANC to mobilize international opposition to apartheid. .He crossed into Bechuanaland(now Botswana) and began what became known as the ANC's "Mission in exile," seeking diplomatic, political and financial support for the movement. Although he was banned and restricted to Johannesburg, he was still allowed to retain his leadership position in the ANC.

With assistance from figures such as Yusuf Dadoo and Frene Giwala , Tambo travelled across Africa , securing travel documents, and meeting with influential leaders like Julius Nyerere from Tanganyika(Tanzania), Kwame Nkrumah from Ghana and Gamal Abdel Nasser from Egypt, presenting ANCs case and seeking support. He settled with his family in Muswell Hill, north London, where he lived until 1990. His exile took a toll on him and not seeing his wife and three children, but his wife Adelaide supported the ANC at home by taking in ANC members arriving from the UK.