John Wallace Shannon (28 April 1862 – 30 January 1926) was an Australian politician. Born in Angaston, South Australia, where he was educated, he became a farmer on the Yorke Peninsula and an auctioneer. He served on Maitland Council, of which he was mayor. In 1896, he was elected to the South Australian House of Assembly for Yorke Peninsula, transferring to Wallaroo in 1902. He left the Assembly in 1905. In 1912, he was appointed to the Australian Senate as a Liberal Senator for South Australia, filling the casual vacancy caused by the death of Labor Senator William Russell. This was the first time a state government had successfully replaced a Senator with a Senator of a different party, after Labor's failed attempt in 1907 to appoint James O'Loghlin to succeed Joseph Vardon. Defeated in 1913, he was elected in 1914 with over 95% of the vote due to the death of Labor Senator Gregor McGregor, which left the Labor Party with only five nominees. They directed the sixth vote to Shannon, resulting in an easy return to the Senate. He joined the Nationalist Party when it formed in 1917, and retired from the Senate in 1919. Shannon died in 1926.[1]