Thongloun Sisoulith (Lao: ທອງລຸນ ສີສຸລິດ; born 10 November 1945) is a Lao historian and politician serving as General Secretary of the Lao People's Revolutionary Party since 15 January 2021 and President of Laos since 22 March 2021.
 Thongloun was born and educated in Houaphan province, before receiving education in Leningrad and Moscow in the Soviet Union. During the Laotian Civil War, he supported the Pathet Lao as a teacher. He then became the Deputy Minister of Foreign Affairs in 1987 which lasted to 1992, where he then served in numerous other posts in government. In 2001, he became the Deputy Prime Minister of Laos before becoming the Minister of Foreign Affairs in 2006. Described as a 'moderate' by the U.S embassy in Vientiane, Thongloun helped improve Laos-United States relations, which was welcomed in 2009 by Senator Jim Webb and in 2010 by Hillary Clinton; while also improving Laos' relationship with China and Vietnam. In 2016, he became the Prime-minister of Laos where he undertook anti-corruption campaigns. He then became the General Secretary of the LPRP and the President in 2021.
 Thongloun Sisoulith was born in the Houaphan province of Laos on 10 November 1945 in the Kingdom of Laos when it was under French control. He went on to study at Pedagogical College of Neo Lao Hak Sat in Houaphan from 1962 to 1969. He was further educated in the Soviet Union and Vietnam. In addition to Lao, he speaks Vietnamese, Russian and English. After finishing graduating, he received a doctor of philosophy in history and a master of arts. From 1973 to 1978, Thongloun studied a Master of Linguistics and Literature at the Gerzen Pedagogy Institute in Leningrad, Soviet Union. Then from 1981 to 1984, he studied a PhD in History of International Relations at the Academy of Social Sciences in Moscow.
 During the Laotian Civil War, Thongloun served with the Communist Pathet Lao as a teacher. From 1967 to 1969, Thoungloun served in Educational Department of the Neo Lao Hak Sat as a senior member, before in 1969 he became a member of the Office of the Representative of the Neo Lao Hak Sat in Hanoi, North Vietnam. He then returned to and from 1978 to 1979, where he served as a lecturer at the National University of Laos following the Communist takeover of Vientiane in 1975. He also headed the Russian language programme at the university.
 Throughout his years in government, he has an extensive list of appointments. He was Deputy Minister of Foreign Affairs from 1987 to 1992, Minister of Labour and Social Welfare from 1993 to 1997, and a member of the National Assembly from 1998 to 2000. He became Deputy Prime Minister and President of the State Planning Committee on 27 March 2001, and he was additionally appointed as Foreign Minister on 8 June 2006, replacing Somsavat Lengsavad. He was chosen to become Prime Minister of Laos at the 10th Party Congress on 23 January 2016.
 After Thongloun became the Prime Minister of Laos, he began anti-corruption campaigns in the Lao government. From April 2016 to February 2017, the State Inspection Authority made 25 arrests related to corruption. Under Thongloun, the government auctioned off BMW-7 series and Mercedes-Benz cars issued by the government and replaced them with Toyota Camrys. During this time corruption in Laos decreased, but after 2017 corruption in Laos became worse.
 On 23 July 2018, a saddle dam part of the Xe Pian-Xe Namnoy hydropower project on the Mekong river in Champassak province collapsed, killing 71 people whilst displacing 14,440 - making it one of Laos' worst dam disaster in history. The dam was being worked on by Laos, Thailand and South Korea, with there being warnings of the dam's unsafety in preceding days. As Prime Minister, Thongloun postponed several meetings and travelled to the affected area in Sanamxay district to oversee relief efforts.
 On 4 January 2020, Thongloun represented Laos in Hanoi at the 42nd meeting of the Vietnam – Laos Inter-Governmental Committee with the Vietnamese Prime Minister. During the meetings, he praised Vietnam's economy, with both countries agreeing to strengthen ties and cooperation between each other. During the COVID-19 pandemic, Laos cooperated with both Vietnam and Cambodia, with Thongloun holding phone calls with his Cambodian and Vietnamese counterparts Hun Sen and Nguyễn Xuân Phúc. At the 36th ASEAN summit on 26 June 2020, he represented Laos where he spoke on the success of ASEAN during the COVID-19 pandemic. On 10 June, he praised the National Taskforce Committee for its handling of the COVID-19 pandemic in Laos following 59 days of no new cases of COVID-19, as well as support from other countries such as China, United States and Vietnam.
 In August 2020, he urged the media to continue "defeating the fake, deceptive, and harmful news" on social media sites. This was interpreted by international media as a way to tell the media in Laos to not report negatively on the government. On 13 December 2020, Thongloun spoke to the United Nations on how Laos continues to follow the Paris Agreement, as well as other policies which aim to reduce carbon emissons. He also asked for support from other nations to assist Laos reach these targets. 
 At the 11th National Congress of the Lao People's Revolutionary Party on 15 February 2021, he was elected the party's general secretary, and hence the de facto leader of Laos, becoming the first civilian with no military background to be general secretary. Thongloun was sworn into office on 22 March 2021, replacing previous leader Bounnhang Vorachith after he retired. Phankham Viphavanh replaced Thongloun as Prime-minister.
 Following his swearing in as General Secretary and President, Thongloun vowed to create economic growth and reduce poverty in Laos by working with the Lao People's Revolutionary Party (LPRP).  After his swearing into the role, he enjoyed popular support due to his handling of the COVID-19 pandemic and his anti-corruption initiatives. In March 2021, Laos began using the Russian Sputnik V COVID-19 vaccine as the main vaccine during its vaccination programmes.
 On 3 December 2021, he and President of China Xi Jinping opened the new Boten–Vientiane section of the Lao-China railway. Laos however faces rising debt to China, with half of Laos' external debt being owned to China. At the 27th Future of Asia conference in Tokyo on 27 May 2022, Thongloun downplayed concerns over a Chinese debt-trap.
 Under Thongloun, Laos found itself balancing its relationships between China and Vietnam. On 26 May 2023, following the Russian invasion of Ukraine as well as tensions between China and Taiwan, Thongloun warned that they had the chance to escalate into larger scale wars.