António Luís Santos da Costa GCC GCIH (European Portuguese: [ɐ̃ˈtɔni.u ˈkɔʃtɐ, ɐ̃ˈtɔnju -]; born 17 July 1961) is a Portuguese lawyer and politician who has served as President of the European Council since 2024. He previously served as Prime Minister of Portugal from 2015 to 2024 and Secretary-General of the Socialist Party from 2014 to 2024.

Born in Lisbon, Costa was Secretary of State for Parliamentary Affairs from 1995 to 1997, Minister of Parliamentary Affairs from 1997 to 1999, Minister of Justice from 1999 to 2002, Minister of Internal Administration from 2005 to 2007, as well as Mayor of Lisbon from 2007 to 2015.

Costa was elected secretary-general of the Socialist Party in 2014. Costa's near 9-year tenure as prime minister is the second longest, with Costa also being the longest-serving politician in government functions, in Portuguese democracy, and the longest of any Iberian Peninsula national leader in the 21st century. On 7 November 2023, Costa resigned following an investigation involving members of his government in connection with alleged corruption and malfeasance in handling lithium mining and hydrogen projects in the country. The President of Portugal decided to dissolve Parliament and called for a snap election. Costa stayed as Prime Minister in a caretaker capacity until 2 April 2024, when he was succeeded by Luís Montenegro.

In December 2024, Costa succeeded Charles Michel as President of the European Council. As President of the European Council, Costa reaffirmed support for Ukraine during the Russian invasion of Ukraine.

António Luís Santos da Costa was born on 17 July 1961 in Lisbon, Portugal, the son of writer Orlando da Costa and journalist Maria Antónia Palla. He is of Portuguese and Goan descent. In Goa, Costa is affectionately known as Babush, a word in Konkani meaning 'a young loved one'.

Costa graduated from the Faculty of Law of the University of Lisbon in the 1980s when he first entered politics and was elected as a Socialist deputy to the municipal council. He completed the mandatory military service in 1987 and later practised law briefly from 1988, before entering politics full-time.

António Costa joined the Socialist Youth in 1975, at the age of fourteen. In the 1982 local elections, Costa was elected as a member of the Lisbon municipal assembly, being re-elected in 1985 and 1989. In the 1991 legislative election, Costa was elected as member of the Assembly of the Republic from the district of Lisbon.

For the 1993 local elections, Costa was picked as the mayoral candidate for the municipality of Loures, a suburb of Lisbon. This contest threw national attention because Costa did a campaign stunt by promoting a race between a Ferrari and a donkey to highlight the difficulty in roads and transportation to Lisbon, and to point for the necessity of better roads and a subway connection to Loures. Costa narrowly lost the mayoral race to the Unitary Democratic Coalition (CDU) candidate by a 35 to 34 percent margin.