William Motti (born 25 July 1964 in Bondy) is a retired French decathlete. He was a two-time French champion at a time when Christian Plaziat was the foremost French multi-eventer.
His personal best of 8164 points were achieved at the Summer Olympics in Barcelona 1992. He represented his country twice at the Olympics, coming fifth in 1984 and seventh in 1992. He also competed at the 1987 World Championships in Athletics and the 1993 IAAF World Indoor Championships. His only international medals were a silver in the high jump at the 1981 European Athletics Junior Championships and a gold in the B-final at the 1987 European Cup Combined Events. His final international outing came at the 1994 European Athletics Championships, where he failed to finish.
He received a two-year doping ban from mid-1990 to 1992. He was later expelled from the German-led "Decathlon Team" group in 1994 for refusing to take a drug test.