1. William James Sidis

Born in America in 1898, William James Sidis was a wunderkind extraordinaire, gifted with an astounding IQ estimated between 250 and 300. This polyglot went to a grammar school when he was only 6 years old and graduated just within 7 months.
As if that wasn’t impressive enough, at the age of 9, he was already a Harvard student, but since he was too young, he was advised to take a couple of years off just to give his personality some time to catch up and be on a par with his intellect. At the age of 11, he became the youngest student to have ever enrolled at the Harvard University. He graduated cum laude at the age of 16, and entered Harvard Law School at 18.