The Grand Master Society stands as the most exclusive, extremely high IQ society. The society aims to have members who achieved Grand Master level on the high range IQ tests.

The minimum requirement to enter the Grand Master Society is a performance on an acceptable high range IQ test of at least five standard deviations above the mean of the general population. This performance corresponds to the following baseline scores:

IQ 175, sd 15 (Wechsler scale)
IQ 180, sd 16 (Stanford-Binet scale)
IQ 220, sd 24 (Cattell scale)

The Grand Master Society was established by Hankyung Lee, MD in 2012 as the Five Sigma Society. Currently, the society has been managed by YoungHoon Kim.