Guillaume Plessis (born 16 January 1985) is a former professional footballer who played as a midfielder.
Plessis started his career with Lens. In January 2005, he joined Premier League club Everton on a six-month deal but failed to make a first team appearance. He has also played for Clermont Foot and Martigues.
Plessis was part of the France U17 squad for the 2002 UEFA European Under-17 Championship.
Plessis's younger brother Damien was also a professional footballer.