German philosopher Karl Marx, perhaps more than any individual, had the greatest influence on the political situation of the 20th century. The founder of communism, his revolutionary theory
blended history, economics, and politics, and proposed the overthrow of capitalism and its substitution by a "dictatorship" of the masses.
Although he was trained in law, philosophy, history, and political economy, Marx spent much of his impoverished working life as a journalist. His expulsion from several European countries was a direct consequence of his radical journalistic style explicitly criticizing governments. He settled in London where he published the first volume of "Das Kapital" in 1867. In later life, Marx enjoyed some financial security thanks to an annuity from Friedrich Engels, his lifelong friend with whom he developed the Marxist theory.
Actually communism was not a significant movement during his lifetime. In fact, it was not until Lenin adapted Marx's themes to clarify the ideals of the Bolshevik Revolution that communism emerged.