Charles Darwin is a rather controversial person in the history of science. On one hand, he's the first person in the world who actually presented the theory of origins of life and species that is both alternative to theological version and, at the same time, is heavily unsubstantiated by his practical research. On the other hand, his theory is widely criticized both by theologians and by a number of biologists. But, nevertheless, Darwin's theory dominates in modern biology and no one can suggest any worthless alternative to it.
Obviously, the biggest impact among all sciences, Darwin's theory has made on biology, especially its evolutionary part. In his monumental paper, famous as "On the origins of species", Charles Darwin was the first one in the world to raise the issue of natural selection, i.e. an evolutionary process that consists in surviving and further evolving of the species which are most adapted and appropriate to the natural conditions they live in. He also improved the evidence basis of Lamarck's concept of evolution and Lyell's concept of uniformitarianism.
Most people tend to associate Darwin's theory only with the development of biology. However, Darwin's works effected several other sciences, especially political science, sociology and economics. The term social Darwinism is widely known in the political and social sciences, despite Darwin had never written papers on these issues. The main theorists of this area tried to apply principles of natural selection in the human society and advocated the idea that only strongest and cleverest people are to create the fate of humanity and that the rules of social life in human and animal society are the same. Also, Darwin's theory is a base for modern eugenics, laissez-faireism and militarism.
In economics the influence of Darwin's theory is especially strong in neoclassic concepts of competition and in libertarian economic thought. In these theories Darwinism is used as biological confirmation of the necessity of the free market without regulation and of its role in maximization of general utility. Also, in his famous work "The Theory of Economic Development" Schumpeter used Darwin's approach to the evolution as grounding of economic development of mankind and reasoning of the process of innovations.
To sum up, regardless of personal attitude to Charles Darwin and his ideas, one must admit the great impact of Darwin's theory on numerous aspects of modern science.