Karl Marx (1818-1883) was the founding leader, along with Frederick Engels, of the modern revolutionary workers movement. Together with Engels he drafted the Communist Manifesto, the program of that movement. A founder of the Communist League (1848-52), Marx played a prominent role in the 1848-49 revolution in Germany. He was the founding leader of the General Council of the International Working Men's Association (1864-76), often called the First International. The writings of Marx and Engels have provided the political foundation for the actions of proletarian revolutionists worldwide for more than a century and a half.

Frederick Engles (1820-1895) was the founding leader, along with Karl Marx, of the modern revolutionary workers movement. Together with Marx he drafted the Communist Manifesto, the program of that movement. A founder of the Communist League (1848-52), Engels played a prominent role in the 1848-49 revolution in Germany. He was, with Marx, a founding leader of the General Council of the International Working Men's Association (1864-76), often called the First International. After the death of Marx in 1883, Engels led the revolutionary wing of the Second International, founded in 1880, until his own death in 1895.