Gwyneth Johnstone (18 June 1915 – 8 December 2010) was an English painter who worked on oil and created landscapes containing individuals in modern landscapes starting from the 1950s. Born as the illegitimate daughter to the musician Nora Brownsford and the artist Augustus John, she enrolled at the Slade School of Fine Art and later the Académie de la Grande Chaumière. Johnstone's work was exhibited in art galleries across the United Kingdom and abroad from the 1960s to the late 2000s.