Karl Schapper (December 30, 1812 in Weinbach – April 28, 1870, London) was a German socialist and labour leader. He was one of the pioneers of the labour movement in Germany and an early associate of Wilhelm Weitling and Karl Marx.
Karl Friedrich Schapper was born on December 30 in Weinbach. His father, Christian Schapper, was a priest. Karl Schapper studied forestry in Giessen. As a student, he joined a radical fraternity, and in 1832, he participated in an insurrection known as Frankfurter Landsturm. The would-be revolutionaries seized an arsenal and wanted to overthrow the Frankfurt diet and proclaim a republic. Schapper was imprisoned, but after three months, he managed to escape, making his way to Switzerland. There he worked as a forestry worker and typesetter. He joined the radical organisation 'Young Germany' and became a follower of the utopian communist Wilhelm Weitling. 'Young Germany' was modelled on, and affiliated with, Giuseppe Mazzini's 'Young Italy', and in 1834, Schapper participated in Mazzini's attempt at an armed invasion of Savoy from Switzerland. This was Mazzini's second attempt; like the first, in 1833, it was unsuccessful. Schapper was once again imprisoned.
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 1836, Schapper was deported from Switzerland for his political activities and went to Paris, France. He joined the French section of 'Young Germany' and the communist 'League of the Banned', soon renamed 'League of the Just'. It was later renamed the 'Communist League', on the initiative of Wilhelm Wolff. The League maintained relations with French utopian communist Étienne Cabet and the Neo-Babouvists. In 1839, the League was implicated in an unsuccessful insurrection by the 'Society of the Seasons', led by Auguste Blanqui and Armand Barbès. Schapper, who had been involved, was caught and imprisoned. In 1840 he was expelled from France and went to London, England, where he re-organised the Communist League. In spite of the failure of the Blanquist insurrection, its organisational model left a lasting impression on Schapper's mind.