Karl Friedrich Schapper (30 December 1812, Weinbach – 28 April 1870, London) was a German socialist and labour leader.
On his release, Schapper resumed his activities in 'Young Germany' and was associated with the exiled German democrat Georg Fein (1803–1869) in setting up workers' educational circles.
In England, Schapper was involved in organising the German Workers Educational Association and the Fraternal Democrats, with Chartist leader Julian Harney.
The Fraternal Democrats promoted republicanism and democracy and attempted to give aid to the many radical political refugees in London; they thus helped forge links among the revolutionaries of different countries.
However, in 1850, a bitter quarrel led to a split, with Marx and Engels on one side and Karl Schapper and August Willich on the other.
Marx argued for building a mass workers' movement for the future; Schapper and Willich wanted to prepare for further insurrections.
Schapper and Willich formed their own group, the Communist Central Committee, modelled on the conspiratorial Blanquist organisations they knew from the 1830s.
His long-standing contacts with French, British, Swiss, Italian, Belgian and American radicals, socialists and trade unionists were a valuable asset to Marx.
Karl Schapper was important for several reasons: As a communist of working-class background, he was one of the pioneers of the labour movement in Germany.
As a member of the League of the Just, Schapper helped forge links between German socialists and the radical French communist and Blanquist groups of the 1830s and '40s.
In the 1840s, Schapper helped build bridges between German socialists and the radical wing of the British Chartist movement.