Archibald Joseph Cronin (19 July 1896–6 January 1981) was a Scottish novelist, dramatist and writer of non-fiction who was one of the most renowned storytellers of the twentieth century. His best-known works are The Stars Look Down, The Citadel, The Keys of the Kingdom and The Green Years, all of which were adapted to film. He also created the Dr. Finlay character, the hero of a series of stories that served as the basis for the long-running BBC television and radio series entitled Dr. Finlay's Casebook.

Cronin was born at Rosebank Cottage in Cardross, Dunbartonshire, the only child of a Protestant mother, Jessie Cronin, and a Catholic father, Patrick Cronin, and would later write of young men from similarly mixed backgrounds. His paternal grandparents were the proprietors of a public house in Alexandria. His maternal grandfather, Archibald Montgomerie, was a hatter who owned a shop in Dumbarton. After their marriage, Cronin's parents moved to Helensburgh, where he attended Grant Street School. When he was seven years old, his father, an insurance agent and commercial traveller, died from tuberculosis. He and his mother moved to her parents’ home in Dumbarton, and she soon became the first female public health inspector in Scotland.

Cronin was not only a precocious student at Dumbarton Academy who won many prizes and writing competitions, but an excellent athlete and footballer. From an early age, he was an avid golfer, a sport he enjoyed throughout his life, and he loved salmon fishing as well. The family later moved to Yorkhill, Glasgow, where he attended St. Aloysius' College. Due to his exceptional abilities, he was awarded a scholarship to study medicine at the University of Glasgow in 1914. He was absent during the 1916-1917 session for naval service and graduated with highest honours in 1919, being awarded an M.B. and a Ch.B.. Cronin went on to earn additional degrees, including a Diploma in Public Health (1923) and his MRCP (1924). In 1925, he was awarded an M.D. from the University of Glasgow for his dissertation, entitled "The History of Aneurysm."