John Creyghton Ainsworth-Davis (23 April 1895 – 3 January 1976) was a Welsh surgeon and sprint runner who won a gold medal in the 4 × 400 m relay at the 1920 Summer Olympics.

During World War I he first served as a captain with the Rifle Brigade and then as pilot in the Royal Flying Corps.

[citation needed] At the 1920 Summer Olympics Ainsworth-Davis ran the third leg for the British 4 × 400 m relay team, which won the event.

[1][4] After graduating from University of Cambridge Ainsworth-Davis studied medicine at St. Bartholomew's Hospital and played music at a nightclub to support his family.

He could not make time for sport, and retired from competitions after placing fourth in the 440 yards at the 1921 AAA Championships.