Sébastien Gagnon (born May 21, 1973) is a Canadian businessman and former politician and soldier.
Gagnon was elected as a Bloc Québécois member of the House of Commons of Canada in a 2002 by-election.
Gagnon was born in Metabetchouan, Quebec.
Before entering politics, he was an entrepreneur and executive manager.
Gagnon served in the Canadian Army from 1991 to 1995.