Oussama "Ous" Mellouli (Arabic: أسامة الملولي; born February 16, 1984) is a Tunisian swimmer who competes in the freestyle and medley events. He is a three-time Olympic medalist, is an African record holder, and trains with the USC Trojans team based at the University of Southern California, where he went to school and swam collegiately.
Oussama Mellouli became the 1500 m freestyle World champion at the 2009 World Aquatics Championships with a winning time of 14:37.28, then the second best performance of all time. Mellouli is the gold medalist in the 1500 freestyle at the 2008 Olympics, the bronze medalist in the 1500 freestyle at the 2012 Olympics, and the gold medalist in the 10 km marathon swim at the 2012 Olympics. Mellouli tested positive in a 2006 drug test, after which his performances in the 2007 World Championships were nullified.