Terence Tao
Australia
Australian mathematician Terence Tao reportedly scored an IQ of 230 on a childhood test -- the highest ever recorded. At age 2 he was teaching mathematics to 5-year-olds; at 10 he competed in the International Mathematical Olympiad and won a gold medal at 13, the youngest ever to do so. He became a full professor at UCLA at 24 and received the Fields Medal in 2006. Known for groundbreaking contributions such as the Green-Tao theorem on prime distributions, he is widely regarded as the greatest living mathematician.