John Robert Ducker (born 12 June 1934) is a former cricketer who played first-class cricket for South Australia from 1952 to 1963.
John Ducker was a wicket-keeper who played most of his matches for South Australia when the state team’s principal keepers, Gil Langley and Barry Jarman, were away on national duty.
He was a useful batsman whose best season was 1959-60, when he scored 489 runs at an average of 37.61, with five fifties and a highest score of 76 against New South Wales.