Terence Tao

Remember that famous William James "equation":

Well imagine being around this guy. Let's see: he finished his bachelor's and masters at 17, his Ph.D. from Princeton at 20, and was a Full Professor at UCLA at 24. By all accounts this guy is the Math stud at this point in time. Fortunately, he is apparently a very nice guy.

Actually, a lot of Fields Medalists were young phenoms, so his being a tenured Full Professor at 24 is not unusual in that population.