William Gallacher was a Scottish trade unionist, activist and communist. He was one of the leading figures of the Shop Stewards' Movement in wartime Glasgow and a founding member of the Communist Party of Great Britain. He served two terms in the House of Commons as one of the last Communist Members of Parliament.

Red Clydeside was the era of political radicalism in Glasgow, Scotland, and areas around the city, on the banks of the River Clyde, such as Clydebank, Greenock, Dumbarton and Paisley, from the 1910s until the early 1930s. Red Clydeside is a significant part of the history of the labour movement in Britain as a whole, and Scotland in particular.