Collier Mountain is a mountain in the Ridge and Valley region of the Appalachian Mountains, located in Allegany County, Maryland. The 1,457 feet (444 m) ridge is approximately 5 miles (8.0 km) southeast of Cumberland. It runs 6 miles (9.7 km) northeast from the North Branch Potomac River near its confluence with Patterson Creek to Murley Branch south of Breakneck Hill.