Since there is no good answer, I will post my thoughts. First, background. As many people in Soviet Union, I studied various parts of Marxism for many (more than 10) years. I was a good student, A's in all subjects, and unlike many, I actually read what the man wrote. So I believe that I know Marxism at least as well as a Professor of Marxism in a major US University (lots of them do not know even the "Gotha Program" or "Marx's letter to J. Weydemeyer in New York" , where he introduced the concept of "Proletarian Dictatorship". None of the Professors I spoke with could formulate the 11-th thesis of Feuerbach: "Philosophers have hitherto only interpreted the world in various ways; the point is to change it".
So to my answer. There is no other scientist in the World, past of present, who has been so politicised -- for obvious reasons. Marx created (basically singlehandedly) Political Science, the theory of class struggle for power. For this he used many classical parts of science: Economy, Philosophy, etc. He did not contribute much to these parts, but he showed how they can be used and interpreted in terms of political science. In particular, in terms of Economics theory, which basically dealt, as described by the famous African-Russian writer Pushkin, with questions like "как государство богатеет и чем живёт, и почему не нужно золота ему, когда простой продукт имеет" (a very rough translation: "how the state gets richer and how it lives, and why it doesn't need gold when it has a simple product"), Marx did not contribute much over Smith and Ricardo. But he found a strong (for him and his followers at least) connection between the Economics theory and Political Economy. Similar - in Philosophy. He did not overdo Hegel or even Feuerbach. But he created "Dialectical materialism.