David Ramsay (1883 – 1948) was a British socialist activist.
Born in Edinburgh, Ramsay became a patternmaker and joined the Amalgamated Society of Engineers. He joined the Social Democratic Federation and then its successor, the British Socialist Party (BSP). However, by the start of World War I, he had joined the Socialist Labour Party (SLP) and had relocated to Leicester. He was a fervent opponent of the war, and was fined £100 in 1916 for trying to prevent people from joining the Army.
The SLP was heavily involved in the Clyde Workers' Committee and, although he did not succeed in starting such a movement in Leicester, Ramsay supported similar initiatives across the country. He became treasurer of the Shop Stewards' and Workers' Committees organisation, within which he led efforts to organise the unemployed and was involved in organising ex-servicemen. In 1919, police claimed that he had given a seditious speech, advocating using machine guns to start a revolution. Ramsay denied the details, claiming that words had been added to his speech, but was jailed for five months.
Ramsay supported the October Revolution, and became the treasurer of the Hands off Russia movement. He was involved in the negotiations to form the Communist Party of Great Britain (CPGB), being one of the leading opponents of it attempting to affiliate to the Labour Party. Although he lost the debate, he attended the 2nd Congress of the Communist International as a shop stewards' delegate. In order to do so, he had to obtain a passport, under the cover story that he wished to emigrate to Argentina and, before doing so, visit relatives in Norway (actually a Bolshevik based there). His request was taken to the Home Secretary, who consulted colleagues but surprisingly decided to grant it. Following the Congress, he stayed in Russia for a while, working for the Comintern, and frequently travelled between there and the UK.