Fort Louvois is a fortification built between 1691 and 1694, during the reign of Louis XIV, on the Chapus islet, and is about 400 metres off shore in the town of Bourcefranc-le-Chapus in the department of Charente-Maritime, France. The fort sits opposite the citadel of Château d'Oléron on the island of Oléron.
Since 1972 the fort has been the site of a museum of oyster farming, and there are oyster beds next to the causeway that joins the fort to the shore.