John Clarkson Maddison (4 September 1921 – 29 August 1982) was a New South Wales politician, Attorney General, Minister for Justice and Deputy Leader for the Liberal Party of New South Wales in the cabinets of Robert Askin, Tom Lewis and Sir Eric Willis until the Liberal party lost the 1976 election.

Maddison was first elected to the New South Wales Legislative Assembly for the Electoral district of Hornsby in 1962 until 1973 and thereon as member for Ku-ring-gai until his retirement in 1980.

Maddison was commissioned as a Lieutenant in the 2nd Australian Imperial Force, 53rd Anti-Aircraft Regiment, on 2 August 1942, serving in Borneo and the Philippines.

[1] Maddison joined the Liberal Party in 1954, becoming Secretary and president of Pymble branch and a member of the state executive from 1958 until 1962.

As Attorney General Maddison represented Australia as deputy leader of the Geneva conference in 1975 and delegate to Australian Constitutional Convention in Hobart in 1976.

[1] Maddison held Ku-ring-gai for a further two elections until his retirement in 1980, causing a by-election that was won by future Liberal Premier of New South Wales, Nick Greiner.

[6] In opposition, Sir Eric Willis appointed Maddison as Shadow Minister for Finance and Federal Affairs from 28 May 1976 to 16 December 1977.