Thabo Mvuyelwa Mbeki (Xhosa: [tʰaɓɔ ʼmbɛːki]; born 18 June 1942) is a South African politician and economist who served as the president of South Africa from 14 June 1999 to 24 September 2008, when he resigned at the request of his party, the African National Congress (ANC). Before that, he was deputy president under Nelson Mandela from 1994 to 1999.

The son of Govan Mbeki, an ANC intellectual, Mbeki has been involved in ANC politics since 1956, when he joined the ANC Youth League, and has been a member of the party's National Executive Committee since 1975. Born in the Transkei, he left South Africa aged twenty to attend university in England, and spent almost three decades in exile abroad, until the ANC was unbanned in 1990. He rose through the organisation in its information and publicity section and as Oliver Tambo's protégé, but he was also an experienced diplomat, serving as the ANC's official representative in several of its African outposts. He was an early advocate for and leader of the diplomatic engagements which led to the negotiations to end apartheid. After South Africa's first democratic elections in 1994, he was appointed national deputy president. In subsequent years, it became apparent that he was Mandela's chosen successor, and he was elected unopposed as ANC president in 1997, enabling his rise to the presidency as the ANC's candidate in the 1999 elections.

While deputy president, Mbeki had been regarded as a steward of the government's Growth, Employment and Redistribution policy, introduced in 1996, and as president he continued to subscribe to relatively conservative, market-friendly macroeconomic policies. During his presidency, South Africa experienced falling public debt, a narrowing budget deficit, and consistent, moderate economic growth. However, despite his retention of various social democratic programmes, and notable expansions to the black economic empowerment programme, critics often regarded Mbeki's economic policies as neoliberal, with insufficient consideration for developmental and redistributive objectives. On these grounds, Mbeki grew increasingly alienated from the left wing of the ANC, and from the leaders of the ANC's Tripartite Alliance partners, the Congress of South African Trade Unions and South African Communist Party. It was these leftist elements which supported Jacob Zuma over Mbeki in the political rivalry that erupted after Mbeki removed the latter from his post as deputy president in 2005.

As president, Mbeki had an apparent predilection for foreign policy and particularly for multilateralism. His pan-Africanism and vision for an "African renaissance" are central parts of his political persona, and commentators suggest that he secured for South Africa a role in African and global politics that was disproportionate to the country's size and historical influence. He was the central architect of the New Partnership for Africa's Development and, as the inaugural chairperson of the African Union, spearheaded the introduction of the African Peer Review Mechanism. After the IBSA Dialogue Forum was launched in 2003, his government collaborated with India and Brazil to lobby for reforms at the United Nations, advocating for a stronger role for developing countries. Among South Africa's various peacekeeping commitments during his presidency, Mbeki was the primary mediator in the conflict between ZANU-PF and the Zimbabwean opposition in the 2000s. However, he was frequently criticised for his policy of "quiet diplomacy" in Zimbabwe, under which he refused to condemn Robert Mugabe's regime or institute sanctions against it.

Also highly controversial worldwide was Mbeki's HIV/AIDS policy. His government did not introduce a national mother-to-child transmission prevention programme until 2002, when it was mandated by the Constitutional Court, nor did it make antiretroviral therapy available in the public healthcare system until late 2003. Subsequent studies have estimated that these delays caused hundreds of thousands of preventable deaths. Mbeki himself, like his Health Minister Manto Tshabalala-Msimang, has been described as an AIDS denialist, "dissident", or sceptic. Although he did not explicitly deny the causal link between HIV and AIDS, he often posited a need to investigate alternate causes of and alternative treatments for AIDS, frequently suggesting that immunodeficiency was the indirect result of poverty.

His political descent began at the ANC's Polokwane conference in December 2007, when he was replaced as ANC president by Zuma. Although his term as national president was not due to expire until June 2009, he announced on 20 September 2008 that he would resign at the request of the ANC National Executive Committee. The ANC's decision to "recall" Mbeki was understood to be linked to a High Court judgement, handed down earlier that month, in which judge Chris Nicholson had alleged improper political interference in the National Prosecuting Authority and specifically in the corruption charges against Zuma. Nicholson's judgement was overturned by the Supreme Court of Appeal in January 2009, by which time Mbeki had been replaced as president by Kgalema Motlanthe.

Mbeki was born on 18 June 1942 in Mbewuleni, a small village in the former homeland of Transkei, now part of the Eastern Cape. The second of four siblings, he had one sister, Linda (born 1941, died 2003), and two brothers, Moeletsi (born 1945) and Jama (born 1948, died 1982). His parents were Epainette (died 2014), a trained teacher, and Govan (died 2001), a shopkeeper, teacher, journalist, and senior activist in the African National Congress (ANC) and the South African Communist Party (SACP). Both Epainette and Govan came from educated, Christian, land-owning families, and Govan's father was Sikelewu Mbeki, a colonially appointed headman. The couple had met in Durban, where Epainette had become the second black woman to join the SACP (then still called the Communist Party of South Africa); however, while Mbeki was a child, his family was separated when Govan moved alone to Ladismith for a teaching job. Mbeki has said that he was "born into the struggle", and recalls that his childhood home was decorated with portraits of Karl Marx and Mahatma Gandhi. Govan named him after senior South African communist Thabo Mofutsanyana.

Mbeki began attending school in 1948, the same year that the National Party was elected with a mandate to legislate apartheid. The Bantu Education Act was implemented towards the end of his school career, and in 1955 he arrived at the Lovedale Institute, an eminent mission school outside Alice, as part of the last class which would be permitted to follow the same curriculum as white students. At Lovedale, he was a year behind Chris Hani, his future colleague and rival in the ANC. Mbeki joined the ANC Youth League at age fourteen and in 1958 became the secretary of its Lovedale branch. Shortly afterwards, at the start of his final year of high school, he was identified as one of the leaders of a March 1959 boycott of classes, and was summarily expelled from Lovedale. He nonetheless sat for matric examinations and obtained a second-class pass.