Sir Walter McLennan Citrine, 1st Baron Citrine, PC (August 22, 1887, Wallasey - January 22, 1983, Brixham) was a British trade unionist and politician.

Citrine was an electrician by trade, becoming Mersey District secretary of his trade union, the Electrical Trades Union, in 1914. Twelve years later he became general secretary of the Trade Union Congress, holding the post for twenty years, including through World War II. He was also president of the International Federation of the Trade Unions 1928-45 and president of the World Trade Union Conference in 1945.

Citrine strengthened the TUC's influence over the Labour Party. He opposed plans by the Labour Government in 1931 to cut unemployment benefits and as a result led the campaign to have Ramsay MacDonald to be expelled from the party. He supported Clement Attlee's government's policy of nationalisation and served on the National Coal Board and served as chairman of the Central Electricity Board 1947-57. He was granted a peerage in 1947.