Artist and social commentator. Born in Dalkeith (Midlothian). He owned a Barber's Shop in Edinburgh's Parliament Square (1771-85) and was noted for his humorous caricatures of Edinburgh's worthies, including important figures of the Scottish Enlightenment, which now form an extensive historical record. He went on to convert his shop into a studio and made portraiture his full-time occupation. Kay portrayed individuals from across the social strata, from the academia and the law, to beggars, fish-wives and criminals, including Deacon William Brodie (1741-88).
He is buried in an unmarked grave at Greyfriars churchyard, although a memorial stone was unveiled nearby in 2005 by author Alexander McCall Smith (b. 1948), who also unveiled a plaque outside Kay's former home at 227 High Street.