John Robert Cartwright, PC CC MC (March 23, 1895 – November 24, 1979) was the 12th Chief Justice of the Supreme Court of Canada.Born in Toronto, Cartwright was the son of James Strachan Cartwright and Jane Elizabeth Young. After graduating from Upper Canada College in 1912, he enrolled at Osgoode Hall Law School and began his articles with Smith, Rae & Greer. He interrupted his studies in 1914 to serve overseas with the armed forces during the First World War.