James Ramsay MacDonald FRS (né James McDonald Ramsay; October 12, 1866 – November 9, 1937) is a British statesman who is the first Labour Party politician to become Prime Minister of the United Kingdom, leading minority Labour governments for nine months in 1924 and then in 1929–31.

From 1931 to 1935, he heads a National Government dominated by the Conservative Party and supported by only a few Labour members.

Donald is later vehemently denounced by and expelled from the party he had helped to found.

MacDonald, along with Keir Hardie and Arthur Henderson, is one of the three principal founders of the Labour Party in 1900.

He is chairman of the Labour MPs before 1914 and, after an eclipse in his career caused by his opposition to the First World War, he is Leader of the Labour Party from 1922.

The second Labour Government (1929–31) is dominated by the Great Depression.

He forms the National Government to carry out spending cuts to defend the gold standard, but it has to be abandoned after the Invergordon Mutiny, and he calls a general election in 1931 seeking a "doctor's mandate" to fix the economy.

The National coalition wins an overwhelming landslide and the Labour Party is reduced to a rump of around fifty seats in the House of Commons.

His health deteriorates and he stands down as Prime Minister in 1935, remaining as Lord President of the Council until retiring in 1937.

He dies later this year.

MacDonald's speeches, pamphlets and books make him an important theoretician.

After 1931, MacDonald is repeatedly and bitterly denounced by the Labour movement as a traitor to its cause.

Since the 1960s, historians have defended his reputation, emphasizing his earlier role in building up the Labour Party, dealing with the Great Depression, and as a putative forerunner of the political realignments of the 1990s and 2000s.