James (Jeremiah) Griffiths CH PC (19 September 1890 – 7 August 1975) was a Welsh Labour Party politician who served for 34 years as a Member of Parliament (MP).

Griffiths was a pacifist and while campaigning against the Great War met fellow socialist Winifred Rutley, and they married in October 1918.

At the age of 29, he left the colliery on a miner's scholarship (1919–1921) to the Central Labour College, London, where at the same time Aneurin Bevan and Morgan Phillips were studying.

Despite the defiance of the party leadership, the vote boosted Labour's popularity by demonstrating its support for the report's recommendations.

During the long period in opposition, Griffiths became Deputy Leader of the Labour Party (1955–1959), and spokesman on Welsh affairs.

Amid the Suez Crisis of 1956, he made an important speech opposing the underhanded tactics of the then Prime Minister Anthony Eden in which he stated: "This is for our country a black and tragic week... an unjustifiable and wicked war".

[5] At Wilson's instigation, Griffiths established the Welsh Office and laid the foundations for the role until the 1966 general election, whereupon he returned to the backbenches.

Though by now suffering from ill-health, Griffiths avoided resigning from the House of Commons, because he feared that if he did so, Labour would lose a by-election in Llanelli.