David Lloyd Johnston (born June 28, 1941) is a Canadian academic, author, and statesman who served as Governor General of Canada from 2010 to 2017, the 28th since Canadian Confederation.

Johnston was born and raised in Ontario, studying there before enrolling at Harvard University and later Cambridge and Queen's universities. He went on to work as a professor at various post-secondary institutions in Canada, eventually serving administrative roles as dean of law at the University of Western Ontario, principal of McGill University, and president of the University of Waterloo. At the same time, Johnston involved himself with politics and public service, moderating political debates and chairing commissions in both the federal and provincial spheres, his most renowned position in that field being the chairmanship of the inquiry into the Airbus affair. He was in 2010 appointed as governor general by Queen Elizabeth II, on the recommendation of then Prime Minister of Canada Stephen Harper, to replace Michaëlle Jean as viceroy and he occupied the post until succeeded by Julie Payette in 2017. At the time, Johnston was predominantly praised as a worthy choice for the Queen's representative, though his appointment was denounced by some Quebec sovereigntists.

As governor general, Johnston was entitled to be styled His Excellency while in office and The Right Honourable for life. He was sworn in as a member of the Queen's Privy Council for Canada on March 26, 2018.