One of the world's greatest geniuses was John von Neumann, who was responsible for pathbreaking innovations in a series of fields, including game theory, set theory, quantum mechanics, the atom and hydrogen bombs, and the computer. This wikipedia article seems like a good summary (although I can't follow some of it). It is hard to imagine what his IQ was.
Von Neumann was also an eccentric -- to say the least -- and the article captures some of that:
Although von Neumann unfailingly dressed formally, he enjoyed throwing extravagant parties and driving hazardously (frequently while reading a book, and sometimes crashing into a tree or getting arrested). He once reported one of his many car accidents in this way: "I was proceeding down the road. The trees on the right were passing me in orderly fashion at 60 miles per hour. Suddenly one of them stepped in my path." He was a profoundly committed hedonist who liked to eat and drink heavily (it was said that he knew how to count everything except calories), tell dirty stories and very insensitive jokes (for example: "bodily violence is a displeasure done with the intention of giving pleasure"), and persistently gaze at the legs of young women (so much so that female secretaries at Los Alamos often covered up the exposed undersides of their desks with cardboard.)
In addition, Von Neumann's political ideology was, in his own words, "violently anti-communist, and much more militaristic than the norm". He favored a first strike against the Soviet Union, "believing that doing so could prevent it from obtaining the atomic bomb."
Update: More on von Neumann:
At the age of six, he could divide two 8-digit numbers in his head and converse with his father in ancient Greek. His interests were not confined to mathematics, and accounts tell of him reading all 44 volumes of the universal history by the age of 8.