Tony Tan Keng Yam (Chinese: 陈庆炎; pinyin: Chén Qìngyán; born 7 February 1940) is a Singaporean banker and politician who served as the seventh president of Singapore between 2011 and 2017 after winning the 2011 presidential election.

Prior to entering politics, Tan was a general manager at OCBC Bank. He made his political debut in the 1979 by-elections as a People's Action Party (PAP) candidate contesting in Sembawang Group Representation Constituency and won. He later served as Deputy Prime Minister of Singapore from 1995 to 2005. After resigning from the cabinet in 2005, Tan was appointed deputy chairman and executive director of GIC, chairman of the National Research Foundation, and chairman of Singapore Press Holdings (SPH). He stepped down from all his positions in 2010 before contesting the 2011 presidential election as an independent candidate.

Tan won the 2011 presidential election in a four-way fight and served as the president of Singapore until 2017. He did not seek re-election in the 2017 presidential election, which was reserved for Malay candidates following a constitutional amendment. He officially retired on 1 September 2017 at the end of his presidential term. He was succeeded by Halimah Yacob on 14 September 2017.

Tan was born on 7 February 1940 in Singapore, to Tan Seng Hwee and Jessie Lim Neo Swee. He received his early education at St Patrick's School from 1947 to 1956 and continued at St Joseph's Institution (SJI) from 1957 to 1958. In 1962, he graduated with a Bachelor of Science with first class honours in physics from the University of Singapore, now known as the National University of Singapore (NUS), under a scholarship awarded by the Singapore government. He later completed a Master of Science in operations research at the Massachusetts Institute of Technology (MIT), supported by the Asia Foundation Scholarship. Tan returned to Singapore for a year to teach in the physics department at NUS before pursuing a Doctor of Philosophy in applied mathematics at the University of Adelaide, supported by a research scholarship. He completed his doctoral degree in 1967 with the dissertation title, 'Mathematical Modelling for Commuter Traffic in Cities.'

Returning to Singapore, Tan began his career as a lecturer in the Department of Mathematics at NUS. In 1969, he left academia to work in OCBC Bank as a sub-manager and rose to become a general manager. He quit the bank in 1979 to enter politics. Tan was elected as Member of Parliament (MP) for Sembawang following his victory in the 1979 by-elections. Later in 1979, he was appointed Senior Minister of State for Education. On 1 June 1980, as part of the transition to Singapore's second generation of leaders in a cabinet reshuffle, Tan was appointed Minister for Education. Unlike typical political announcements, the reshuffle was carried out quietly, without farewells or media fanfare. When asked, S. Rajaratnam made it explicit that Tan and S. Dhanabalan's appointments were all part of a broad plan to nurture and experiment with the next generation leaders. Tan was also the Vice-Chancellor of NUS from 1980 to 1981.

Following this, Tan held some key ministerial roles as Minister for Trade and Industry between 1981 and 1986, Minister for Finance between 1983 and 1985, and Minister for Health between 1985 and 1986. At this time, he lobbied for a reduction in the Central Provident Fund (CPF) contributions, a move Prime Minister Lee Kuan Yew had previously indicated would only be undertaken if there were an economic crisis. In his role as Minister for Trade and Industry, Tan was most concerned with how foreign investors would react to a deterioration in labour relations, which would have a negative effect on foreign direct investment. In 1981, he was also against the proposed timing of the Mass Rapid Transit (MRT) project, which was mooted by Ong Teng Cheong. Tan argued that the local construction sector was already overheated and believed that public housing development should take precedence. Responding to public discontent, Tan later scrapped a controversial policy that gave priority in primary school admission to children of better-educated mothers. This move was widely believed to have contributed to the PAP's poor showing in the 1984 general election.

As minister for education from January 1985, Tan led major reforms to modernise Singapore's education system. He promoted English proficiency, bilingualism, and values education, while introducing flexible student placement, greater school autonomy, and expanded access to higher education. His key achievements included the Gifted Education Programme, the shift to English as the main instructional language, single-session schooling, and efforts to address teacher shortages through better pay and training. On 9 March 1985, Tan officially opened the Singapore Petrochemical Complex at Pulau Ayer Merbau. Later that month, Tan cancelled the Graduate Mothers' Priority Scheme, a source of controversy, stating that it was not very likely to be able to achieve its hoped-for effect of encouraging additional births for graduate mothers but had instead created public resentment in large numbers.

Tan also launched the independent schools scheme, a few already existing schools were granted greater independence in matters of staff recruitment, finance, management, and curriculum. Tan introduced the independent school scheme to raise educational standards by allowing top schools greater autonomy to attract top talent and serve as models for others. Launched in 1988, the initiative expanded school choice, promoted innovation, and aligned with meritocratic principles, while also reducing public spending by shifting more education costs to families.