António Luís Santos da Costa is a Portuguese lawyer and politician who served as the 118th prime minister of Portugal from 2015 to 2024, presiding over the XXI (2015–2019), XXII (2019–2022) and XXIII Constitutional Governments (2022–2024).

The prime minister of Portugal is the head of government of Portugal. As head of government, the prime minister coordinates the actions of ministers, represents the Government of Portugal to the other bodies of state, is accountable to parliament and keeps the president informed. The prime minister can hold the role of head of government with the portfolio of one or more ministries. As Portugal is a semi-presidential parliamentary republic, the prime minister is the country's leading political figure and de facto chief executive.