[Anders]

Well, it's probably safe to assume that the smartest people lived in the last century - better nutrition, better education and fewer diseases all play a big part. So I would say that the smartest people are IQ 16-20.

But these people may not be famous! They may have been unable to make good use of their intelligence for other reasons - class, personality, or upbringing. In Sweden we have something similar to the SATs, except anyone may take them, and I remember one year there was a story about the highest-scoring guy being perfectly content working at a burger joint flipping burgers. It gave him the money he needed and he wasn't really interested in going into academia or business. So don't mistake fame for intelligence.