John Paddy Carstairs (born John Keys, 11 May 1910 in London – 12 December 1970 in London) was a prolific British film director (1933–62) and television director (1962–64), usually of light-hearted subject matter. He was also a comic novelist and painter.
The son of Nelson Keys, Carstairs changed his name in order to avoid the appearance of nepotism. He directed 37 films in total. He had a long association with the character of Simon Templar (the character's creator, Leslie Charteris, dedicated the 1963 book, The Saint in the Sun to Carstairs). Aside from directing the 1939 Saint film, The Saint in London, he also directed two episodes of The Saint in the 1960s, making him the only individual (other than Charteris himself) to be connected to both the Hollywood film and British series of The Saint. Carstairs directed many British comedies including many of Norman Wisdom's films.