Harold Joseph Laski (June 30, 1893 – March 24, 1950) was an English political theorist, economist, author, and lecturer, and served as the 1945-1946 chairman of the Labour Party.

After attending Manchester Grammar School and New College, Oxford, Laski became (1922-1936) a member of the executive committee of the socialist Fabian Society, and in 1936 he joined the Executive Committee of the Labour Party. Cowling describes him as a "prolific publicist and journalist."

In 1926 he was appointed professor of Political Science at the London School of Economics. One of his more famous books is Reflections on the Revolution of Our Time (which was dedicated to Edward R. Murrow). He was active on the American university lecture circuit. His 19 year friendship with Supreme Court Justice Oliver Wendell Holmes, begun when he was 23 and Holmes was 75, is reflected in two volumes of correspondence, published in 1953.