The concept of IQ emerged at the beginning of the 20th century, but formal IQ tests such as WAIS (the Weschler test) did not emerge until the 1950’s. (You can visit this site for a brief history of their development: Why were IQ tests developed originally?) Consequently, we don’t have IQ measures for the greatest leaders in history. However, in 2006, psychologist Dean Simonton did a histiometric study of the intelligence of each of the presidents of the United States in an attempt to estimate their IQ’s based on their personalities and achievements. See: Who was the Most Intelligent President in US History? – Intelligence and IQ. From this study, he inferred that most of the US Presidents had an IQ of at least 130.
However, it is probable that very few of the great leaders had IQ that exceeded 160, because people of extremely high IQ tend to be more introverted and interested in pursuing their own goals without the encumbrance of bringing others along with them. This was true of Newton, Einstein, Gödel and most of the great scientists, philosophers, authors, and composers.
It’s worth noting that many influential leaders throughout history, like Julius Caesar, Napoleon Bonaparte and Mahatma Gandhi may not have had exceptionally high IQ scores, but they were able achieve greatness through their vision, leadership skills and character traits. The ability to gain the support of a large number of people and unite them to act toward a shared cause requires excellent communication skills, strong self-efficacy and enough vision to navigate through difficulties to achieve a goal. This requires a significant amount of intelligence, so it’s reasonable to assume that most of the great leaders had an above average IQ, i.e., at least 120. Therefore, it would seem that the estimated ranges presented above are probably close to what we might find if we had actual data.
