Alexander De Croo (Dutch: [aːlɛkˈsɑndər də ˈkroː]; born 3 November 1975) is a Belgian politician and businessman who serves as Administrator of the United Nations Development Programme (UNDP). He was Prime Minister of Belgium from 2020 to 2025. Previously from 2012 to 2020, De Croo served as deputy prime minister in the governments of Elio Di Rupo, Charles Michel, and Sophie Wilmès. During his tenure as deputy prime minister he served as the Minister of Pensions from 2012 to 2014, as Minister of Development Cooperation from 2014 to 2020, and as Minister of Finance from 2018 to 2020. On 1 October 2020, over a year after the 2019 federal elections, the De Croo Government was formed to replace Wilmès' minority government, with De Croo as prime minister.

De Croo was born in Vilvoorde and studied business engineering at the Vrije Universiteit Brussel before attaining an MBA at Northwestern University in the United States. He worked for Boston Consulting Group before starting his own company, Darts-ip, in 2006. De Croo became involved with the Belgian political party Open Vlaamse Liberalen en Democraten (Open VLD), of which he was chairman from 2009 to 2012.

After the 2024 Belgian federal election, De Croo and his party suffered a major electoral defeat. De Croo announced his resignation on 9 June 2024. De Croo remained as caretaker prime minister until the new government was formed on 3 February 2025, being succeeded by Bart De Wever, leader of the N-VA.

Alexander De Croo was born on 3 November 1975 in Vilvoorde in Flemish Brabant, Belgium, and was one of two children of the politician and Minister of State Herman De Croo and his wife Françoise Desguin. In 1993, he attended the Vrije Universiteit Brussel where he graduated in 1998 in Business Engineering. He attended Northwestern University in Evanston, Illinois, in 2002, and completed an MBA at the Kellogg School of Management in 2004. Prior to his political career, De Croo became a project leader at Boston Consulting Group in 1999. In 2006 he founded a new company called Darts-ip that specialized in providing services to intellectual property professionals.

In 2009, De Croo participated for the first time in politics, standing in the 2009 European elections. He received more than 47,000 votes. On 26 October, De Croo became a candidate for the presidency of his political party, Open Flemish Liberals and Democrats (Open VLD), to succeed the transitional party president, Guy Verhofstadt. He chose Vincent Van Quickenborne and Patricia Ceysens as his running mates to compete against Marino Keulen and Gwendolyn Rutten. On 12 December, he was elected president in the second round with 11,676 votes; Marino Keulen received 9,614 votes. His election was considered remarkable as he had almost no previous experience as a politician.

Five months after being elected party leader, De Croo threatened to withdraw the Open VLD from the governing coalition if there was no solution to the constitutional dispute in the Brussels-Halle-Vilvoorde voting issue. After Open VLD's deadline passed the party left the government and then Prime Minister Yves Leterme announced the government's resignation. This was accepted by King Albert II on 26 April 2010. During the elections for the Senate in 2010, De Croo obtained more than 301,000 votes, the third most in the Dutch-speaking constituency and served as a senator until 22 October 2012.

De Croo succeeded Van Quickenborne in the Di Rupo Government as deputy prime minister and Minister of Pensions on 22 October 2012 after Van Quickenborne resigned to become mayor of Kortrijk. In December Gwendolyn Rutten was elected as the new chairwoman of Open VLD.

After the 2014 Belgian federal election and its Federal Government formation, it was decided that he would remain deputy prime minister in the newly formed Michel I Government. De Croo also became Minister of Development Cooperation, Digital Agenda, Telecom and Postal Services while Daniel Bacquelaine took over from him as Minister of Pensions. This government took office on 11 October 2014.