The Wansbeck by-election, 1918 was a parliamentary by-election held for the House of Commons constituency of Wansbeck in Northumberland on 28 May 1918.
The by-election was caused by the death on 20 April 1918 of the sitting Liberal MP Rt Hon. Charles Fenwick, at the age of 68. He had held the seat since the general election of 1885. Fenwick was prominent figure in the Northumberland Miners' Association having first worked as a coal miner at the age of 10. He was one of a large group of miners representatives who refused to join the Labour party.
Fenwick, as a sponsored candidate of the Northumberland miners, had won the seat for the Liberals at every election since the seat was created in 1885. When the Miners Federation of Great Britain voted to affiliate to the Labour party in 1909, Fenwick, retaining the support of the Northumberland miners, contested both 1910 General Elections as a Liberal candidate. The Labour party did not field a candidate against him and at the December 1910 General Election he was returned unopposed. The last contested election in Wansbeck was the January 1910 contest;
Wansbeck Liberal Association adopted Alderman Robert Mason as their candidate to replace Fenwick. Mason was a 60-year-old shipping agent and shipowner with local government and community connections. He was an Alderman of Northumberland County Council and a Justice of the Peace.
As participants in the wartime coalition with Prime Minister, David Lloyd George, the Conservatives chose not to contest the by-election. Given that they normally polled poorly, this was not much of a sacrifice.