Olivier Marceau (born January 30, 1973 in Fontenay-aux-Roses, Hauts-de-Seine) is an athlete from France, who competes in triathlon.
A member of the Poissy Triathlon Club he competed at the first Olympic triathlon at the 2000 Summer Olympics. He took seventh place with a total time of 1:49:18.03.
Four years later, at the 2004 Summer Olympics, Marceau competed again. This time he competed on the Swiss team, placing eighth with a time of 1:52:44.36.