John Wilfrid Greenstock (15 May 1905 – 6 February 1992) was an English first-class cricketer who played in 46 matches in the 1920s, the bulk of these for Oxford University and Worcestershire. Greenstock made his first-class debut for Worcestershire against Northamptonshire at Worcester in August 1924, but was not called upon to bowl a single ball.He played one further match that summer, against Somerset, and this time claimed 4-69 including the wicket of Jack White, but Worcestershire were nevertheless heavily defeated.