John Denis Martin Nunn (born 1955) is a British grandmaster, author, and publisher of chess books. He was born in London and attended Oxford University where he earned his doctorate in mathematics at the young age of 23. After completing his doctorate, Nunn pursued his interest in chess and received the title of International Master in 1975.
His successful performance in several international tournaments allowed him to obtain the grandmaster title in 1978. Nunn was a formidable competitor especially in solving and composing chess problems, earning him several World Chess Solving Championships.
As an author, Nunn penned multiple books on subjects related to chess, such as tactical play and openings. He also ventured into publishing chess books through his company, Gambit Publications.
Despite his impressive accomplishments in chess, Nunn also exhibited proficiency in mathematics. He published a number of papers in academic mathematics journals and was part of a team that solved a century-old problem related to algebraic topology.
From 1978 to 2006, Nunn competed in nine Chess Olympiads for England, earning four team and three individual medals. Throughout his career, Nunn has been known for his dedication to high standards of accuracy and depth both in playing chess and writing about it.