William Adamson (2 April 1863 – 23 February 1936) was a Scottish trade unionist and Labour Party politician.

[1] He led the party into the general election of 1918, which saw Labour gain 15 seats and become the largest opposition party in the House of Commons for the first time; however, there remained uncertainty as to whether Adamson or the leader of the independent Liberals, Donald Maclean could claim to be the true leader of the opposition in the Commons.

[6] In 1919, Adamson was confident that the experience of the First World War would "produce a different atmosphere and an entirely different relationship amongst all sections of our people" and would act as a watershed in the process of social reform.

[1] He stood again in the 1935 election but again failed to take the seat, losing on this occasion to William Gallacher of the Communist Party of Great Britain.

[2] Adamson was married to Christina Myles Marshall (1862–1935), a factory worker, with whom he had two daughters and two sons; one of the latter was killed during the First World War.