Michael Phelps is a retired American swimmer and the most decorated Olympian of all time with 28 medals. His record-breaking performances have earned him numerous accolades, and he is widely regarded as the greatest swimmer ever.
This is based on winning 12 head-to-head matchups with other famous people, but also losing 11 head-to-head matchups.
Most recently Michael Phelps lost a matchup to Joachim Gauck (#1665) voted by someone from Denmark.