John von Neumann
He was born in Hungary, studied in Germany, and after 1930, mainly worked in the United States. In every branch of science he stepped in, he left outstanding results: mathematics, mathematical logic, quantum mechanics, design of computer, the theory of automata, and the theory of games. He was also deeply involved in US military policy as an advisor.
The swiftness of his mind (or the CPU of his brain) is legendary. Whether true or not, it is said that his calculation was faster than any computer of his day. During and after the war, he was involved both in the development of nuclear weapons and of computers. He annoyed Oppenheimer (then the Director of Institute for Advanced Study, Princeton) by bringing in the project of manufacturing IAS computer, against the policy of the Institute. He was also known as a reckless driver.
Despite some (moral, say) misgivings, his contributions to science and technology are immense; and it seems quite silly ("legitimate" in some sense, though) to denouce this type of scientist on moral, social, or political (or whatever) grounds; everything considered, the balance is undeniably on the positive (good) side.
