There have been at least four groups named the Communist League in the UK, in addition to the Communist League of Karl Marx and Friedrich Engels, which was based in London.

The Communist League was the first Trotskyist group in Britain. It was formed in 1932 by former members of the Communist Party of Great Britain from Balham and Tooting in South London, including Harry Wicks . They had been expelled after forming a loose grouping inside the CPGB, known as the Balham Group or the British Left Opposition. They published a monthly newspaper named Red Flag.

In 1933, Trotsky suggested the group should enter the Independent Labour Party, but the leadership decided to attempt to influence the party's members without joining. In 1934, a small group did enter the ILP as the Bolshevik-Leninist Fraction, which C. L. R. James joined. Slow progress led to more splits, with the formation of the entrist Bolshevik-Leninist Group in the Labour Party in 1935.

A second Communist League is a tiny anti-revisionist group highly supportive of Stalin and Enver Hoxha, but rarely for a Stalinist grouping very hostile to Mao Zedong. Formed in 1995, it was led by Bill Bland until his death.

A third Communist League in Britain split from the Marxist Party in 1990, claiming to hold more closely to the ideas of Gerry Healy. It produced the magazine Socialist Futures.

A fourth Communist League in Britain was formed by a split in 1998 from Socialist Action and joined the American Socialist Workers Party's Pathfinder tendency. It maintained a bookshop in The Cut in London. Its members sold The Militant, the paper of the American Socialist Workers Party, which claims many of them work in the strategic meat packing industry.