The Fier (French: le Fier) is a 71.9 km (44.7 mi) long river in the Haute-Savoie and Savoie départements, southeastern France. Its source is at Manigod, in the Aravis Range. It flows generally west. It is a left tributary of the Rhone into which it flows at Seyssel. The Chéran is among its tributaries.