John McKenzie McBain (27 August 1882 – 28 January 1941) was a Scottish trade unionist and political activist. Born in Edinburgh, McBain grew up in Elgin before completing an apprenticeship in a foundry in Glasgow. He devoted his spare time to wrestling until an injury force him to quit the sport, and in 1906 he decided instead to focus on trade unionism. He joined the Associated Iron Moulders of Scotland and the Independent Labour Party (ILP), but Tom Bell convinced him to leave the ILP and join the Marxist Socialist Labour Party.