If he can win one more Gold Medal in an individual event, he beats out a dude from the 2'nd century B.C. That's pretty cool.
http://www.sbnation.com/2016/8/9/12419516/michael-phelps-gold-medal-record-leonidas-of-rhodes
http://www.sbnation.com/2016/8/9/12419516/michael-phelps-gold-medal-record-leonidas-of-rhodes