There is at least one who never had his IQ tested:
As far as we known today, Albert Einstein has never done any IQ test. Thus his IQ is unknown!
In the 20ies scientists had tried to estimate the IQ of deceased personalities such as Mozart (1756-1791) and Goethe (1749-1832) by means of biographic data; thus they wanted to estimate Albert Einstein’s IQ, too. The value estimated for Einstein was between 160 and 180. But this rough estimation can not count as Einstein’s IQ!
Source: Hans-Josef Küpper. VARIOUS THINGS ABOUT ALBERT EINSTEIN
There are many ways to estimate IQ. Some rely on education, some on activity field etc.
In 1926, psychologist Dr. Catherine Morris Cox - who had been assisted by Dr. Lewis M. Terman, Dr. Florence L. Goodenaugh, and Dr. Kate Gordon - published a study "of the most eminent men and women" who had lived between 1450 and 1850 to estimate what their IQs might have been. The resultant IQs were based largely on the degrees of brightness and intelligence each subject showed before attaining the age of 17.
Cox also found that different fields have quite widely varying average IQs for their acknowledged leading geniuses. Displayed below are there calculated Deviation IQs (the number in brackets is the number in the sample considered):
Philosophers (22) average IQ 160; Scientists (39) 159; Fiction writers (53) 152; Statesmen (43) 150; Musicians (11) 149; Artists (13) 153; Soldiers (27) 136.
Source: Ulf Norlinger. Estimated IQs of some of the Greatest Geniuses