Martin Brian Mulroney ( muul-ROO-nee; born March 20, 1939) is a Canadian lawyer, businessman, and politician who served as the 18th prime minister of Canada from 1984 to 1993.

Born in the eastern Quebec city of Baie-Comeau, Mulroney studied political science and law. He then moved to Montreal and gained prominence as a labour lawyer. After placing third in the 1976 Progressive Conservative leadership election, he was appointed president of the Iron Ore Company of Canada in 1977. He held that post until 1983, when he successfully became leader of the Progressive Conservatives. He then led the party to a landslide victory in the 1984 federal election, winning the second-largest percentage of seats in Canadian history (at 74.8 percent) and receiving over 50 percent of the popular vote. Mulroney later won a second majority government in 1988.

Mulroney's tenure as prime minister was marked by the introduction of major economic reforms, such as the Canada–United States Free Trade Agreement, the goods and services tax (GST) that was created to replace the manufacturers' sales tax, and the privatization of 23 of 61 Crown corporations including Air Canada and Petro-Canada. Mulroney sought Quebec's endorsement of the constitutional amendments twice by first introducing the Meech Lake Accord (proposed recognizing Quebec as a distinct society and extending provincial powers) and then the Charlottetown Accord (proposed extensively changing the constitution, including recognition of Quebec as a distinct society); both failed to be ratified. The Meech Lake Accord's demise sparked a revival of Quebec separatism, leading to the rise of the Bloc Québécois. In foreign policy, Mulroney strengthened Canada's ties with the United States and opposed the apartheid regime in South Africa, leading an effort within the Commonwealth to sanction the country. Mulroney's tenure was marked by the Air India Flight 182 bombing, the largest mass killing in Canadian history, though his response to the attack came under criticism. Mulroney made environmental protection a key focus of his government, securing a treaty with the United States on acid rain and moving Canada to become the first industrialized country to ratify the Convention on Biological Diversity. His government added significant new national parks (Bruce Peninsula and South Moresby) and passed the Canadian Environmental Assessment Act and the Canadian Environmental Protection Act.

The unpopularity of the GST and the controversy surrounding its passage in the Senate, combined with the early 1990s recession, the collapse of the Charlottetown Accord, and growing Western alienation that triggered the rise of the Reform Party, caused a stark decline in Mulroney's popularity, which induced him to resign and hand over power to his cabinet minister, Kim Campbell, in June 1993. In the election later that year, the Progressive Conservatives collapsed, being reduced from a majority government of 156 seats to two, largely as a result of the emergence of the Bloc and Reform parties. In his retirement, Mulroney serves as an international business consultant and sits on the board of directors of multiple corporations. Although he places average or above-average in rankings of Canadian prime ministers, his legacy remains controversial. He has been criticized for his role in the resurgence of Quebec nationalism and accused of corruption in the Airbus affair, a scandal that would only gain prominence several years after he left office.