The 2003 Progressive Conservative leadership election was held on May 31, 2003, to elect a leader of the Progressive Conservative Party of Canada. Peter MacKay was elected as leader to replace former Prime Minister Joe Clark, who then retired as party leader. In the end, five candidates emerged as challengers for the leadership by the convention date. Two other candidates had participated in the race but both withdrew as contestants before the vote. Quebec Member of Parliament (MP) André Bachand withdrew his candidacy from the race due to financial concerns and backed Peter MacKay. Former Cabinet Minister and Quebec MP Heward Grafftey also withdrew his candidacy from the race due to health concerns and backed David Orchard.

Peter Gordon MacKay is a Canadian lawyer and politician. He was a Member of Parliament from 1997 to 2015 and has served as Minister of Justice and Attorney General (2013–2015), Minister of National Defence (2007–2013), and Minister of Foreign Affairs (2006–2007) in the Cabinet of Canada under Prime Minister Stephen Harper. MacKay was the final leader of the Progressive Conservative Party of Canada, and he agreed to merge the party with Stephen Harper's Canadian Alliance in 2003, forming the Conservative Party of Canada and making MacKay one of the co-founders of the current conservative wing of Canadian politics.