John Cassimar Treanor (17 August 1922 – 7 November 1993) was a first-class cricketer who played for New South Wales between 1954 and 1957.

A leg-spin bowler, Treanor made his first-class debut in the Sheffield Shield against Queensland in 1954–55, taking 5 for 146 and 3 for 69 (including a hat-trick) in the drawn match.

He took 28 wickets at an average of 30.25 in 1956–57,[5] and took his best figures of 5 for 36 in the tied match against Victoria,[6] but that was his last season of first-class cricket.

[8] In the Second World War Treanor served as a sapper with 2/4 Field Company.

[9] He married Norma Durrington in Lismore, New South Wales, in June 1947.