William MacLeod Speirs (8 March 1952 – 23 September 2009) was a Scottish trade union leader, a socialist and internationalist. He was General Secretary of the Scottish Trades Union Congress. Speirs was a key figure in left-wing Scottish politics, chairing the Scottish council of the Labour party at the 1987 general election, and being a prominent member of various groups of the Bennite left, e.g. the Labour Co-ordinating Committee and .