Montancy (; unofficial also Montancy-Brémoncourt) is a commune in the Doubs department in the Bourgogne-Franche-Comté region in eastern France.
The commune lies east of Saint-Hippolyte at the east end of the department near the Swiss border. The village of Brémoncourt lies in the valley of the Doubs at 430 m, and Montancy on the plateau at 900 m.