Stephen Joseph Harper (born April 30, 1959) is a Canadian politician who served as the 22nd prime minister of Canada from 2006 to 2015. He is to date the only prime minister to have come from the modern-day Conservative Party of Canada, serving as the party's first leader from 2004 to 2015. Since 2018, he has also been the chairman of the International Democracy Union.

Harper studied economics, earning a bachelor's degree in 1985 and a master's degree in 1991 at the University of Calgary. He was one of the founders of the Reform Party of Canada and was first elected to Parliament in the 1993 federal election in the riding of Calgary West. He did not seek re-election in 1997, and instead joined and later led the National Citizens Coalition, a conservative lobbyist group. In 2002, he succeeded Stockwell Day as leader of the Canadian Alliance, the successor to the Reform Party, and returned to Parliament as leader of the Official Opposition. In 2003, Harper negotiated the merger of the Canadian Alliance with the Progressive Conservative Party of Canada to form the Conservative Party of Canada and was elected as the party's first leader in 2004. In the 2004 federal election, the new party lost to the Liberal Party led by Paul Martin. After Martin's government was defeated in a motion of no confidence, Harper led the Conservatives to a minority government in the 2006 federal election.

During Harper's premiership, he faced the "In and Out" scandal, lowered the goods and services tax (GST), and passed the Federal Accountability Act, the Québécois nation motion, and the Veterans' Bill of Rights. After the Conservatives won a larger minority in the 2008 federal election, Harper prorogued Parliament to avoid defeat by a proposed coalition of opposition parties, passed the Economic Action Plan of major personal income tax cuts and infrastructure investments in response to the Great Recession, introduced the tax-free savings account, and ordered military intervention during the First Libyan Civil War. In March 2011, a no-confidence vote found his government to be in contempt of Parliament, triggering a federal election in which the Conservatives won a majority government. Harper subsequently withdrew Canada from the Kyoto Protocol, repealed the long-gun registry, privatized the Canadian Wheat Board, and enacted the Anti-terrorism Act, 2015. In foreign policy, his government launched Canada's Global Markets Action Plan, negotiated trade deals including the Comprehensive Economic and Trade Agreement (CETA), and initiated military operations abroad against ISIL and in response to the Russo-Ukrainian War. Harper's Conservatives also faced political controversies in the Robocall scandal and the Canadian Senate expenses scandal, and confronted the Idle No More movement.

In the 2015 federal election, the Conservative Party was defeated by the Liberal Party led by Justin Trudeau. Harper officially stepped down as party leader in October 2015, and resigned his seat in August 2016. Since then, he has taken on a number of international business and leadership roles, including founding a global consulting firm, appearing in U.S. and British media, and being elected as chairman of the International Democracy Union, an international alliance of centre-right to right-wing political parties. Harper ranks average to above-average in rankings of prime ministers of Canada.

Harper was born and raised in the Town of Leaside, now a neighbourhood of Toronto, Ontario, the first of three sons of Margaret (née Johnston) and Joseph Harris Harper, an accountant at Imperial Oil. The Harper family traces its ancestral roots back to Sledmere, a village in Yorkshire, England, with Harper's 4th great-grandfather Christopher having emigrated to Nova Scotia in 1774, where he later served as justice of the peace in the area that is now New Brunswick.

Harper attended Northlea Public School in Leaside and, later, John G. Althouse Middle School and Richview Collegiate Institute, both in Etobicoke, Toronto. He graduated from high school in 1978, and was a member of Richview Collegiate's team on Reach for the Top, a televised academic quiz show for high school students. Harper studied at the University of Toronto's Trinity College before moving to Alberta. In an attempt to establish independence from his parents, Harper dropped out of the University of Toronto and then moved to Edmonton, Alberta, where he found work in the mail room at Imperial Oil. Later, he advanced to work on the company's computer systems. He took up post-secondary studies again at the University of Calgary, where he completed a bachelor's degree in economics in 1985. He later returned there to earn a master's degree in economics, completed in 1991. Throughout his career, Harper has kept strong links to the University of Calgary. Trained as an economist, Harper was the first prime minister with an economics degree since Pierre Trudeau and the first prime minister without a law degree since Joe Clark.

Harper became involved in politics as a member of his high school's Young Liberals club. He later changed his political allegiance because he disagreed with the National Energy Program (NEP) of Pierre Trudeau's Liberal government. He became executive assistant to Progressive Conservative (PC) Member of Parliament (MP) Jim Hawkes in 1985 but later became disillusioned with the party and the government of Brian Mulroney, citing the administration's economic policy. He left the PC Party the next year.

Harper was then recommended by the University of Calgary's economist Bob Mansell to Preston Manning, the founder and leader of the right-wing populist Reform Party of Canada. At that time, Harper "didn't see himself as a politician", Mansell told CBC News in 2002, adding, "Politics was not his first love."